Schiit Jotunheim "R" - Direct-Drive Amplifier for SR1a "Earfield™ Monitors" - Review

Review written by Ian Dunmore (@Torq)

Introduction

Schiit Audio’s new “Jotunheim R”, launched on 1/21/2020, is a dedicated, high-performance, compact direct-drive amplifier for the RAAL-requisite SR1a ribbon-driver “EarField™ Monitor” headphone. It features several of Schiit’s recent innovations, including their Nexus(tm) topology and modular source/input-card support.

If you’re not already familiar with the SR1a, you should stop here and read the following review on them; if you are, then you’ll already know that, until the arrival of the Jotunheim R, they:

• Required a 100W into 8 ohms (150W into 4 ohms) speaker/power amplifier to drive them.

• The amplifier connects to the headphone via an “interface” box that a) adapts their native 0.2 ohm impedance to something that won’t instantly short out, or trip the protection on, said amplifier and b) applies a compensation curve to account for the frequency response of the step-baffle ribbon headphone driver.

The “Direct Drive” part of the Jotunheim R means that the interface box is no longer needed. Instead you connect the SR1a directly to the Jotunheim R, which provides both the necessary amplification and applies the compensation curve, and removes the need for speaker cables. All you need is a source … and the Jotunheim R can even act as an all-in-one solution using an option internal DAC card. This opens up the use of the SR1a to a more convenient and fully transportable solution, particularly useful for the originally intended “studio/mixing” use case for the RAAL-requisite headphones.

Note: The Jotunheim R is specifically designed for the SR1a headphones. It is NOT intended to be used with conventional headphones - that’s what the original Jotunheim (no “R”) is for.

The unit used for this review is my personal unit, purchased directly from Schiit Audio, and equipped with the optional True-Multibit DAC card. Prior to the production release, Schiit had kindly loaned me a production-qualifier unit so as to get some earlier exposure to what, ultimately, turned out to sound identical to the shipping units.

The gear chain/equipment used in this review can be found here, and the music I use in my reviews and evaluations is listed here.

Specifications

Jotunheim R is not a conventional headphone amplifier, as the SR1a load is almost a dead-short (0.2 ohms impedance), so some of the more typical specifications you might expect to see, such as output impedance (<0.015 ohms, for the curious), or power output into varying loads either don’t make sense (this is only for the SR1a) or have to be considered differently.

Ultra-low impedance means very high currents. A conventional, highly-demanding, headphone, such as the HiFiMan Susvara, might pull 290 mA for 120 db/SPL output. The Jotunheim R can deliver 13,200 mA, at peak, into the SR1a. To cope with that, the power-supply is backed with 120,000 uF of capacitance - that’s more than some $3,000, 300W, stereo power-amplifiers! One thing you won’t lack here is power …

Frequency response with the step baffle compensation off is within 0.1 dB across 500 kHz of bandwidth (and of course, from 20 Hz to 20 kHz) and the signal-to-noise ratio is >110 dB (at 3A output).

Features & Functionality

Jotunheim R is, first and foremost, a direct-drive amplifier for the SR1a. It incorporates both the necessary input-switching and volume control to operate as a fully integrated pre/power amp, or all-in-one.

There are three possible “inputs” or sources, specifically a balanced (XLR) input, a single-ended input (RCA) and an optional internal, USB-fed, multibit DAC card, all selected from the front panel.

The unit can also act as a passive pre-amp. This means no gain - just pure analog volume attenuation. The purely passive pre-amp function ensures that you won’t suddenly have the very-high-current capable output stage suddenly driving a downstream amplifier. It also means that the Jotunheim R does not convert single-ended inputs to balanced pre-outputs (nor vice-versa). The pre-amp function can be enabled or disabled via a front-panel toggle.

Finally, the unit lets you bypass the step-baffle compensation necessary for the SR1a to exhibit a normal, studio-neutral, tonal response. With the existing SR1a you want this switched ON (up position). The “off” selection is intended to provide some level of future proofing - to accommodate the potential elease of circumaural ribbon-driver headphones.

Build

Jotunheim R follows the standard, solid, build for Schiit’s mini-sized components, continuing the J-frame first introduced on the standard Jotunheim, and offered exclusively in black. The top panel features a stylized “R” (for “RAAL”) in place of the normal Schiit “S” logo.

Internally there is room for a single input/source module, like that on Schitt’s other recent amplifier releases - first introduced on the original Jotunheim, that’s now available on the Lyr 3, Asgard 3 and Ragnarok 2 as well.

Like all Schiit components, excepting the micro-line (e.g. Modi, Magni, Vali etc.), this unit has an internal linear PSU fed using a standard IEC cable. This means an internal transformer, which results in both a convenient setup as well as the unit feeling rather substantial.

Note, carefully, the headphone connection. It’s a male 4-pin XLR instead of the female socket you’d find on a conventional balanced-output headphone amplifier. This obviously matches the connector on the cables supplied with the SR1a headphones. The reason it is inverted is to actively prevent you from accidentally connecting regular headphones to the amplifier!

Packages

The basic Jotunheim R package will be familiar to anyone that’s ever purchased from Schiit: You get the unit itself, a standard IEC power-cord and printed manual, supplied in a sturdy, but no-frills, foam-suspended box.

There are two additional (optional) packages available when you order a Jotunheim R:

• An internal True-Multibit DAC card, with a USB input ($200).

• An external Bifrost 2 True-Multibit DAC ($600), which is available at a $99 discount if ordered with the Jotunheim R vs. simply buying it separately ($699).

Both of these options will be covered later in this review. And both are available as independent purchases if you later decided to upgrade.

Sound & Performance

First impressions were of a smooth delivery with clearly more prominent bass and sub-bass than almost everything I’d tried with it previously, excellent impact and slam and amazing detail retrieval - and absolutely retaining, and exploiting, all of the strengths I’d already found that are native to the SR1a themselves. And this was compared to some much more expensive speaker amplifiers (via the interface box).

Even fresh out of the box, and barely at room temperature, Jotunheim R gave a fantastic account of itself. Some very minor hints of sibilance/splashiness were audible, but completely abated somewhere between about 24 and 48 hours of being powered on and run. It also became apparent that while the unit sounds great even when first powered on, giving it five minutes or so to warm-up will see it giving its best - so there’s no need to leave it switched on.

Speaking of warm-up, the unit does not run particularly warm. Even after several hours of listening at rather enthusiastic levels, including some burn-in time at further elevated SPL. An average temperature below that of the human body, and only the internals getting a bit warmer; very easy to live with on the desk or in a rack.

Further Listening …

My primary listening was done using a Chord Blu-Mk2/M-Scaler fed DAVE as the source, something that has already proven its mettle with the SR1a, via both RCA and XLR connections.

The greater bass presence that is clearly evident with the Jotunheim R vs. almost everything I’ve run through the interface box, results in the SR1a exhibiting a tonal profile that is closer to true neutral than their standard “studio/near-field monitor neutral” that they usually deliver. I think this is going to be a more enjoyable rendering for most listeners, and doesn’t require the addition of any EQ processing to achieve here.

As such, the ultimate sound of the Jotunheim R/SR1a combination is close to neutral. The SR1a’s natural tendency towards being a bit bass-light and a little bright is reigned in a fair bit here. While still not realizing bass-levels comparable to the best planar headphones, this is the closest I’ve heard without spending several multiples of the price of the Schiit amp or requiring EQ. And if you do choose to use EQ here, the Jotunheim R won’t be what limits your ability to apply it … it has fantastic control and balance and more than enough power in reserve to make the excursion limits of the headphones your ultimate limiter.

The resolution/detail retrieval my source combination is capable of is equal to, or better than, any other digital setup I’ve heard … and it was all preserved here with as much transparency as is audibly feasible. There was no sense that anything was being lost, nor glossed over, at any point during my listening. Details were readily apparent, such as very low-level noises in the background of recordings (say the movement of chairs or turning of pages in “Introduction et Rondo Capriccioso, Op.28 for Violin and Orchestra (in B minor)” (EMI, Saint-Saëns, Walter Süsskind), that are much harder to discern both with some of the other amplifiers I’ve tried with the SR1a and with flagship conventional headphones driven straight out of DAVE’s headphone output.

Timbral rendering is lifelike and faithful … a notable trait of the SR1a themselves. Where some amplifiers can impart odd timbral artifacts on headphones that are otherwise free of them, and some headphones add a “plasticky” (or alternatively “metallic”) sense to instrumental timbres, there is no sense of that here. My most demanding piano recordings retain an incredibly lifelike sense, from the purest notes played pianississimo to exaggerated fortississimo, or even sforzando, and their discordant overtones, to the point it seems like you’re in the room with the instrument itself.

Transient response is lightning fast. Even with this relatively modestly priced amplifier, it is so fast that it matches or generally beats every other can I have had my ears on (or had on my ears, I guess). The initial impact with percussion, or the bite and attack of a string being plucked, appears with startling immediacy. Fast, ultra-complex pieces, in which the start and end of notes might appear to blend into each other with other combinations of amp and headphone, are clearly separate, delineated and highly articulate here. There is no added decay or reverberation, either from the amplifier or the transducer, while what is present in the recording is absolutely evident.

Macro-dynamics are superlative, hitting hard and fast, with huge swings in the music effortlessly portrayed, be it cannon-fire or a massive orchestral crescendo peaking and the instantly falling silent. Similarly the staccato attack of rapid-fire percussion is precisely delivered, with the snap or boom of each drum-hit being visceral and impactful. No matter how much of a dynamic rollercoaster your chosen music takes you on, the Jotunheim R/SR1a combination easily keeps up.

At the opposite end of the dynamic spectrum, the Jotunheim R manages to exploit the amazing micro-dynamic subtlety that the SR1a are capable of rendering. This is often where the texture in a voice or in the timbre of an instrument is most notable, with tiny fluctuations in level being readily audible, but yet without being exaggerated. Pieces in which the performer is clearly being emotionally affected are often most evident by the soft wavering in the singers voice, or the gravel in their tone, and that is presented with delicacy and precision here.

If the Jotunheim R has one area of its performance that doesn’t quite rise to the greatness of the others, and its hard to think in those terms when the performance is so captivating and convincing to begin with, it would be in the way it presents the soundstage and how the image it renders appears. Now it is, to be sure, vastly more convincing in this regard than any conventional headphone I can name, regardless of what amplifier you pair it with. It can, after all, render actual depth-wise spatial cues such that you can hear “into” the recording and position individual elements in both lateral and depth-wise space. But the stage is a somewhat narrower laterally, and a little less well delineated front-to-back than with the speaker amplifiers I have paired the SR1a with. It’s not a huge difference, but it’s apparent. Though, again, if coming from any other headphone, you’re still going to be amazed at the fact there is actual dimensionality here.

Overall this is an incredibly compelling performance, irrespective of price. It is full of power, detail, and impact, while yielding more natural tone, conveying excellent subtlety and delivering the full emotion of the music. It is engaging, and involving, in a sit-up-and-take-notice fashion as appropriate for the SR1a themselves.

The Jotunheim R won’t change the fundamental nature of the SR1a - they are still an all-out, take-no-prisoners, everything-laid-bare experience. This little box doesn’t round them off or blunt them in any way, shape or form. This is a high-octane performance that will keep you captivated, engrossed and involved. Of course, if all you desired was to sit back, and be gently lulled and cajoled into a dozy haze - you wouldn’t have gone for the SR1a in the first place …

A Word or Two (Hundred) on “Weldenheim” vs. Jotunheim R

“Weldenhiem” was the name given to an early prototype of what ultimately became the Jotunheim R. I’ve seen a couple of reviews and impressions that were based that early prototype, which cited a lack of power/volume and some low-level noise in driving the SR1a.

There are no such issues with the production Jotunheim R, which differs significantly from those early prototypes.

The background here is a black as you could want. Think black cat, in a coal-mine, at night. Turning the unit up to full volume, with nothing playing, or while playing digital silence, results in absolute void. And if music is playing, the Jotunheim R is capable of pushing the SR1a to their excursion limits, with power to spare (to get equivalent power to the headphones, via the interface-box, would require something on the order of a 1000W speaker amplifier - and that’s more than the interface can even handle).

For more details on the evolution from concept, through prototype, to shipping product, Jason Stoddard, co-founder of Schiit Audio, has an entertaining, and fascinating, chapter on the origins of “Weldenheim” (from his book/thread “Schiit Happened: The Story of the World’s Most Improbably Start-Up”, which is well worth reading.

Amplifier Comparisons

I have already covered the performance of power/speaker amplifiers, at several price/performance levels, in my main RAAL-requisite SR1a review. Additionally there is further commentary on other amplifiers in this discussion thread. Rather than repeat those verbatim here, I will focus on higher-level, summary, comparisons specifically and purely to the Jotunheim R.

Note that with all of the amplifiers covered here, except the Jotunheim R, the supplied interface box must be used to drive the SR1a. Thus its presence is implied and assumed in each case.

vs. Single Schiit Vidar (Stereo)

Jotunheim R exhibits more bass presence/impact, has a more neutral (i.e. slightly warmer) tonality, resolves more detail, exhibits more subtlety and resolution with micro-dynamic elements, is faster/has better transient response and yields greater headroom.

The single Vidar does paint a wider image with slightly more depth and more easily discernible depth-wise location.

vs. Dual Schiit Vidar (2x in Monoblock Configuration)

This brings the Vidar’s closer to the bass-delivery of the Jotunheim R, but still does’t quite match it. Tonality gets a hint warmer, but again is not quite a close to true-neutral as the smaller amplifier manages, though macro dynamics do reach a similar level.

The biggest difference is that the dual-Vidar configuration renders an even more palpable, expansive and well delineated stage than either the single Vidar or the Jotunheim R.

vs. Dual Schiit Aegir (2x in Monoblock Configuration)

The Jotunheim R is the much more dynamic and impactful performer here with significantly more headroom and, at higher volumes, with more energetic music, a better sense of “ease”. The resolution advantage was a bit smaller than vs. the Vidar, but is still ahead here.

The dual-Aegir configuration does exhibit a more refined and delicate sound, from the mids up through the treble (a hair smoother). It also exhibits a similar level of stage projection, image stability and instrument/performance placing as the dual-Vidar configuration.

vs. Benchmark AHB2

This is the first/earliest/cheapest point at which I started to find parity with the resolution, speed, detail and precision of the Jotunheim R. Tonally the Jotunheim R is still the preferable rendering for me, with more substantial low-end drive and presence, which lends the music a better sense of body or weight - the Benchmark unit sounds leaner, and drier, which are not traits I think flatters the SR1a. The AHB2 does render a more expansive and stable stage, however, and is slightly more refined in the extreme treble.

vs. Chord Étude

At nearly double the price of the Benchmark amplifier, and seven times that of the Jotunheim R, the Étude marks the point where I feel that I’m getting more out of the SR1a via the interface than without it. That’s a significant illustration of the law-of-diminishing returns!

The tonal presentation here is very close and finally matches the Jotunheim R in terms of low-end presence. There is a little more flesh in the mid-tones, but we’re splitting hairs there. Treble is smoother, and the overall presentation via the Étude is more refined and composed. Which is not to say that Schiit amp lacks refinement, that’s not how I’d characterize it. It’s more a case of going from a formally assumed maximum of “10”, and then suddenly discovering it’s possible to go to “11”; even if it needs a budget akin to buying warp-drive to make the difference.

As a continuing theme the Étude, like the other speaker amplifiers here, is also ahead of the Jotunheim R in terms of stage presentation and imaging. The little Schiit is no slouch in this regard - the combination of it with the SR1a will easily see off any challenge in this regard from ANY other headphone I’ve heard. But the Chord unit does beat even that.

This is the amplifier I ultimately choose to run my SR1a in my primary headphone rig.

Apparent Benefits of Bypassing the Interface Box

The RAAL-requisite interface box uses a passive approach to applying the necessary step-baffle compensation - using banks of large, high-wattage resistors, and a pair of inductors. In contrast the resistors are not necessary with the Jotunheim R, as it can drive the near-short load of the SR1a directly, and the compensation profile is handled actively.

There appear to be some significant benefits to the active approach employed here, and these were principally manifested with the Jotunheim R consistently delivering more detail, speed and exhibiting fabulous micro-dynamic resolution when compared to most of the speaker/power amplifiers I tried. Even the rather more expensive ones. I started to find rough parity around the level of the Benchmark AHB2, and had to step up to units that cost almost double that to get to a point where I felt the speaker-amplifier path was starting to pull ahead.

Source Package Comparisons

The SR1a are incredibly revealing of differences in both ones music and the source used to play it. This makes it far easier to discern even tiny differences between sources. Since you can optionally order the Jotunheim R with either an internal modular DAC, or a discounted Bifrost 2, and as I had both options available, here are some basic observations about their relative performance and overall sound.

w/ True-Multibit DAC Card

As mentioned previously, the Jotunheim R has a modular input board capability, just like Schiit’s other amplifiers. In theory it can use any of the cards made for that slot (balanced D/S DAC, phono stage and the multibit DAC), though currently it can only be directly ordered with either nothing in that slot, or the multibit DAC.

If you’re familiar with Schiit’s Modi Multibit, then you already know most of what you need to know about the sound of the True-Multibit DAC Card. They are fundamentally similar pieces in terms of signature and performance, though the card version can only be driven over USB.

The DAC card provides an enjoyable, slightly warm, rendering, with nice tone, faithful timbre and solid dynamics if a bit less air/space and sparkle in the top-end than I generally like. There’s no fatigue here, and listening is easy and pleasant, but the sound is not as incisive, detailed nor vivid as the Jotunheim R/SR1a are capable of. Low-level details that are readily audible with more capable sources are apparent by their sometimes muted nature or absence. And the specificity of various aspects of the sound, such as tiny changes in tone or timbre resulting from a triangle or drum being hit inconsistently are, again, conspicuous by they apparent absence … lost in the overall reproduction.

It is, however, worth noting that the things I notice missing here weren’t necessarily audible at all with conventional headphones even when using a higher-end source, either. So, while the SR1a makes it easier to discern differences in performance between the multibit DAC card and more capable DACs, the end result is still often better than more expensive DAC/amp pairings with other headphones.

The raw resolution of the Jotunheim R/SR1a combination does mean that any foibles in the recording, or the source, become rapidly apparent, also, and with the multibit DAC card there’s a hint of veil or “gray-ness“ to the reproduction vs. other sources that anyone that’s heard the SR1a can tell you is NOT coming from the headphones.

Overall, this is a pleasant listen, and particularly as a convenience option the internal card makes a lot of sense. It gives you a true one-box solution for driving the SR1a, making for a neater setup, fewer cables, and a more compact and simpler setup - particularly useful in a transportable context, but nice for ever-more-crowded desktops, too. I specified my own Jotunheim R with the multibit DAC card installed for just those reasons.

But, at the end of the day, you’re not realizing the ultimate potential of either the SR1a nor the Jotunheim R here and both are more than worthy of a better source.

w/ Bifrost 2

As the Bifrost 2 is available at a discount when purchased with the Jotunheim R, as since it matches its form-factor, and can exploit the amps balanced input option, it is a natural source to consider as a potential upgrade to either an existing DAC (depending on what you have) and vs. the other Schiit option, the True-Multibit DAC card.

Note that I will be covering the Bifrost 2 in a dedicated review in the near future, so commentary here will be focused on pairing with the Jotunheim R and SR1a.

Comparing the Bifrost 2 with the internal True-Multibit DAC card is made fairly straightforward by grouping both DACs and feeding them from Roon, so that they play completely in sync and with their levels matched. They can then be alternated simply by flipping the source selector on the amp. Though it is not really necessary to do this when comparing them via the Jotunheim R/SR1a pairing as there are some immediately apparent differences even without instant comparison.

For a start, the overall rendering is more vivid, well delineated, and exhibits better clarity; any sense of haziness is gone. The lower registers gain more presence, and both bass and percussion offer more slam and impact. This further shifts the overall tonality of the setup towards plain neutral, which helps with the overall tonal profile of the SR1a for new listeners.

Bifrost 2 is also clearly doing a better job at resolving micro-dynamic nuances and in delivering on the detail present in the source material. There’s a palpable improvement in the emotional subtlety … those low-level variations in volume level apparent in a performers wavering voice as the music and lyrics affect them are more distinctly audible.

Where the DAC module lacks some sense of air and space, Bifrost 2 opens the top end up, giving the perception of better extension and range while also delivering a smoother treble rendition. The DAC card isn’t harsh, but the Bifrost 2 is clearly smoother and more refined all the same. It renders brass-tones, even discordant ones, as brass - retaining their bite but with no hint of steeliness. And higher-pitched, edgy/strained female vocals don’t stray into sibilance.

Stage is rendered in a broader, deeper, more clearly dimensional fashion, than with the DAC card … something the SR1a, unlike almost all other headphones, is readily capable of exploiting! Instruments are better separated and can be placed in both lateral and depth-wise space with a precision and stability that has typically required DACs more of the stature of Schiit’s Yggdrasil to pull-off.

Unsurprisingly, the Bifrost 2 is a more engaging, and technically capable, DAC than the multibit DAC module. Sufficiently so that, for serious listening, if you already had a serviceable DAC, and don’t need all-in-one capability here, then I would be inclined to pass on the internal card option entirely and use one’s existing source until it was possible to put the difference in cost towards a Bifrost 2.

Overall, Bifrost 2 is very impressive in this pairing and compares extremely well to other, more expensive, source options - something I’ll cover in more detail in my Bifrost 2 review. Differences that might not be apparent with more conventional amplifiers and transducers are starkly audible here.

Summary

Schiit’s new Jotunheim R is an excellent, and extremely high-value, way to drive the RAAL-requisite SR1a. Indeed, when it comes down to it, the pairing of Jotunheim R and SR1a outperforms every conventional headphone/amplifier combination I have heard - irrespective of price. You absolutely get the full-fat SR1a experience here, with no muting or blunting and no excuses nor caveats needed.

This is nothing short of a game-changer in terms of knocking down the barriers-to-entry with the SR1a.

The SR1a is not a laid-back, warm, or euphonic headphone; they won’t cosset your ears, coddle your sensitivities, or croon softly in your shell-like. Pairing them with the Jotunheim R will not make them do this either; what it will do is let you experience the SR1a “as nature intended” and without breaking the bank to do so.

The combination of direct-drive, and a slightly different compensation profile, lets the Jotunheim R match, and typically exceed, the realized technical performance of much more expensive amplifiers (that must use the interface box), in a simpler, smaller and much more convenient package.

It isn’t a perfect solution - you may give up a little in the way of refinement vs. some more exotic and expensive power amplifiers. And the staging and imaging performance seems to trail there a little too, though this is still so far beyond anything you’ll hear in that regard on normal circumaural headphones that it is of little consequence.

If you don’t already have a suitable power amplifier, or you do and you want to starting exploring just how far down the rabbit hole the SR1a experience can take you, the Jotunheim R should absolutely be your first port of c