Softears RSV mk2 Review: Reference Revisited

Softears’ original RSV is a very well-regarded “neutral” IEM that, in many ways, ended up predicting the direction IEMs would eventually go a few years after its release. While many audiophiles sang RSV’s praises, there are many in this hobby who aren’t interested in neutrality and instead want their music to be presented with additional excitement. Enter Softears’ new RSV mk2 at $700, which aims to improve upon the original RSV by adding a considerable bass boost in order to satisfy those who felt the original RSV was lacking excitement.

However, the question then becomes: since “RSV” stands for “Reference Series Five,” does the additional bass boost of the RSV mk2 still make it an appropriate entry into a series meant to be tuned for reference listening? Let’s talk about it.

Build, Design, Comfort & Accessories

Touching on accessories first, the Softears RSV mk2 comes with a puck-shaped hard case with a leather exterior. There’s ample room inside for the IEM, cable, and eartips. Though I do typically tend to prefer something pocketable, I have no real issue with this case. I like that, similar to the case of the Volume S, the leather on the outside of the case does add a luxurious touch when holding/handling the case. I do prefer Volume S’s case though, if only because I find rectangular cases easier to fit in a bag with other things due to stackability on multiple sides—the Tetris of it all.

The cable is a slightly plasticky, slightly heavy 4-wire 2pin cable terminating in 4.4mm Pentaconn. Thankfully this cable is quite flexible and avoids tangling very well. However, this is still where my first few gripes arise with the RSV mk2, as this cable seems a bit unnecessarily heavy for a device that’s meant to be portable. It actually reminds me of the stock cable that comes with the Moondrop Cosmo or Audeze’s over-ear headphones like the MM-500; this cable would be totally fine for a more substantial over-ear headphone, but on an IEM this just feels a little bit too chunky.

Additionally, I’m not a fan of the cable terminating with 4.4mm Pentaconn by default. Thankfully Softears includes a very nice 4.4mm to 3.5mm single-ended adapter, which does technically fix the problem. However—and this may be irrational—I don’t like using adapters, especially with supposedly portable products. I’d much rather the cable were 3.5mm single-ended by default and there was a 4.4mm adapter or separate 4.4mm cable included. That said, the adapter itself feels quite premium, and is something I’m glad to have around for when I need one.

Moving on from the cable, we get Softears’ typical complement of eartips: their “Ultra Clear” (UC) liquid silicone tips, and their “Standard/B-Type” black tips. Both have a medium bore size, and sound very similar with the Ultra Clear seemingly having a slightly less damped quality to the upper-most treble, which isn’t to my preference so I opted for the Standard tips which seemed to relax the upper treble a bit more. That said, neither tip was ideal for me, which we’ll get into in the Sound section.

Comfort-wise I think the RSV mk2 is a mixed bag. The shell itself is quite large, so for those with small outer ears it may just not be workable, but honestly even with the largeness of shell the fit was surprisingly very comfortable for me, more so than with other smaller but less ergonomically-molded shells. While yes, it did take a bit of time to work the shell into the correct orientation in my ear, once I found the sweet spot, shell comfort was excellent.

However, because the RSV mk2 is an all-Balanced Armature IEM, it needs a fully or mostly sealed environment to produce bass, so the venting that Softears advertises for this IEM is on the very mild side. As a result, I do experience mild discomfort when inserting the IEM due to pressure build up, but thankfully the shell is vented enough that this equalizes after a few seconds. Compared to unvented IEMs like the Symphonium Helios, it is much more livable both when it comes to this pressurization, as well as the occlusion effect.

Overall the RSV mk2 strikes me as a competent package when it comes to accessories and comfort, with my only real gripe being the default 4.4mm Pentaconn cable. Otherwise, the shell being on the big side might be an issue for some people, but comfort ends up being pretty good for this reviewer, and for its price RSV mk2 shouldn’t have too many negative surprises for buyers.

Sound

As you can see from the measurement, there’s quite a bit of mid-bass, but to me it doesn’t sound quite as bassy as the measurement above suggests. While yes there’s a bit of that rotund, bouncy quality that comes with a mid-bass emphasis around 80-150 Hz, the excess in the 150-250 Hz region seems to balance this bulbous quality somewhat and instead just add an overall thickness to the sound that’s honestly preferable to me vs. the bouncy, disjointed bass of a typical 100 Hz bass shelf.

There’s still a mild over-presence of bass, in that the bump of kick drums and the fundamentals of bass guitars sound physically closer than elements in the midrange like vocals and guitars, but overall the presentation of elements that span these two regions is still reasonably balanced; the midrange is only slightly overpowered, and only on certain recordings.

An interesting aspect of the bass profile here—perhaps due to Softears’ choice to provide some kind of venting on the RSV mk2—is that it’s not all that sub-bassy. Personally I detect quite a bit less energy under 50 Hz than the graph suggests, but this is a benefit to me, not a detriment. Excess sub-bass is often responsible for a cloying slowness that comes with a lot of IEMs, but this is a problem that RSV mk2 doesn’t have. Despite the bass boost, it’s a pretty snappy listen, with better physicality than I expected from this amount of bass.

A potential benefit of the extra bass is that RSV mk2 tends to be a little more “full range” sounding at lower listening volumes compared to something with a bass shelf at a lower frequency or with less bass overall. RSV mk2 definitely sounded more punchy and complete at lower-than-typical listening levels for me, with the only downside being that the midrange still didn’t come quite forward enough at low volumes to be the star of the show.

One could say RSV mk2’s bass has most of the good aspects of a prominent bass shelf—warmth, punchiness, size—while for the most part minimizing the downsides effectively. It just has a bit too much presence to be what I’d call truly “neutral,” but that may not matter as much to people who are more focused on their IEM portraying the music enjoyably than it sounding bereft of coloration.

The midrange is where the original RSV shined, near-perfectly predicting the current trend of IEM midrange tuning. Thankfully it seems whatever made the original special was maintained here, and the RSV mk2 has a pretty awesome midrange tuning in isolation. This does also mean that there’s not really much to talk about when it comes to midrange; only so many ways to say “it sounds great.” Similar to other IEMs that have come around in the past year or so that are all following the new trend of neutral midrange in IEMs, RSV mk2 provides a natural, tonally-correct presentation for basically anything that occupies the midrange.

My only gripe with the midrange is that, despite easily being the best part of this IEM, it sometimes takes a backseat due to the bass overshadowing it sometimes. With older rock recordings, folk music, and classical music, there’s enough of a lack of bass in the source material that the midrange gets to be the star of the show, but for most modern music (and interestingly, some jazz) I found myself a bit disappointed that an IEM with “reference” technically in the name ended up calling attention to bass more often than to the timbral accuracy of things like vocals, string instruments, and horns.

That said, this is a very minor gripe when considered from another perspective, which is that few IEMs provide an engaging bass profile while also having solid midrange linearity. I would say the interplay between the two regions, while slightly favoring bass, never sounds grossly imbalanced or “basshead.” The midrange is great, the bass is pretty solid too, and the two play together reasonably well.

The treble is, like most IEMs, going to be a toss-up. As mentioned, I didn’t enjoy the treble profile with the included Ultra Clear silicone tips, and preferred it a bit more with the Standard/B-type tips, but honestly even with those I found it to be a little gritty sounding due to a bit too much in the upper treble. I ended up preferring a few narrow bore tips I had around like Final E, KBEAR KB08, or DUNU Candy tips, all of which worked really well and totally calmed the upper treble enough for RSV mk2’s treble to be quite enjoyable without EQ.

Now, with all of those tips, I do I detect a slight excess in the low treble to my ear, enough so that snare drums have a slight bit of extra paperiness to them, and male vocals that aren’t de-essed enough can have a bit of extra crashiness to certain sibilant vowels (S, F, T sounds), but this is a very minor compromise that rarely actually bothered me.

Importantly, this same elevation lent an important push to the attack of kick drums that helped balance the mid-bass forwardness rather well, so it’s a trade off that I’d say is probably worth making.

I must say, the RSV mk2’s treble is unlike a lot of other sets with this similar “neutral midrange + bass boost” approach because frankly most of them go for much larger upper treble boosts in a misguided attempt to balance the presentation. In basically all cases this just makes the IEM less coherent for me, so it’s nice that RSV mk2 avoids this common pitfall, because it ends up coming across more coherently integrated from top to bottom because of it.

Zooming out and getting an overall picture here, the RSV mk2 strikes a damn reasonable balance. It’s not perfectly neutral, but it’s close enough that I think most people will find something to like about it. Frankly, I’m glad I took a while to review it, because it’s the kind of IEM that wasn’t noticeably impressive on first listen, and its benefits weren’t immediately obvious until I took time to compare it to other options.

Comparisons

Vs. DUNU DaVinci

As far as “bassy with neutral mids” IEMs go, DaVinci is the first one that came to mind when it came to comparing the RSV mk2 to another IEM in this style, so let’s talk about the differences here.

DaVinci is a near-perfect example of the issue I mentioned earlier, where IEMs with a lot of sub-bass have a preternatural slowness to them. While RSV mk2 has more mid-bass, it sounds less bassy and less slow than DaVinci; the difference in sub-bass and treble seems to make the RSV mk2 a noticeably snappier, nimbler listen that does better keeping up with fast changes in music or accurately representing the decay of kick drums.

DaVinci has a tendency to make the entire sonic landscape it presents sound expansive and chill (in a good way), but when the music itself is not chill or expansive, this character still gets imparted, and it sounds inappropriate. The RSV mk2, by contrast, tends to retain more of the character of the music itself, while still having an inviting sense of warmth and bass-forwardness to it.

Additionally, DaVinci sounds a bit less coherent because it’s got this bassy, warm, thick downslope to its presentation, but then a huge treble spike around 13-14 kHz that is seemingly there to try to balance out the thickness. For one, I don’t think this peak is sufficient to balance the rest of the warmth it has, but also the peak itself is the least likable part of this IEM. It makes DaVinci sound very grainy and offputting, especially due to the contrast in size between this peak and the relaxed 6 kHz region.

This is yet another area RSV mk2 absolutely improves on, having a much smaller delta between the upper treble and lower treble, thus sounding more put together overall, while still having what I’d call a neutral level for its overall treble region.

RSV mk2 gets my vote as the better IEM here. It does the whole “bassy” approach to neutral in a way that is overall more balanced and minimizes the downsides that bassier IEMs tend to have. It’s also much more comfortable and much better looking, for my taste anyway.

Vs. Hisenior Mega5EST

While claiming to adhere to Harman’s controversial in-ear target, Mega5EST actually landed on something much more like Harman’s near-universally praised over-ear target, and in doing so achieved something extremely likeable and easy to listen to.

And I think the RSV mk2 does this just as well, if not even better than the Mega5EST, depending on the listener’s priorities. What I mean is that RSV mk2 hits the same hallmarks—generous bass shelf, neutral midrange, slightly boosted treble—but with a different execution that some users may find preferable to Mega5EST’s specific approach.

For example, if a listener found Mega5EST’s bass underwhelming, its presentation lacking intensity, or its upper treble a bit too bright, I think the RSV mk2 handles these aspects better.

RSV mk2’s bass hits considerably harder, both because it has more upper bass relative to sub-bass, and because its lower treble has a slight forwardness that highlights the attack of kick and snare drums. But RSV mk2’s upper treble is also slightly more relaxed, while potentially being a bit more versatile for listeners who found Mega5EST’s treble hard to get to a goldilocks zone with tip rolling.

For me, Mega5EST was pretty much bright up top no matter what, because its treble makes users choose between a lot of 12-13 kHz (wide bore tips) or a lot of 10 kHz (narrow bore tips). RSV mk2 has a mild elevation up there, but users can either choose to get more (wide bore tips) or less (narrow bore tips) of that 12-13 kHz treble peak than with the stock tips, without introducing any extra peaks or dips. This strikes me as something that may be a bit more versatile since it’s not only swapping between extremes.

Additionally, I found RSV mk2’s comfort to be just a bit better than Mega5EST’s, likely due to the nozzle profile on Mega5EST being a little on the wider/stubbier side. So overall, I still think Mega5EST is an incredibly solid IEM, and maybe one that is more likely to be heard as “neutral,” but I find the RSV mk2 to have similar strengths to Mega5EST while potentially minimizing a few of its downsides for some listeners when it comes to bass tactility or overall excitement.

Vs. Softears Volume S

Many people asked for this comparison, and I was a bit curious why outside of them being from the same manufacturer, because the IEMs didn’t really seem similar on paper… but there’s commonality to approach here, which we’ll talk about in the conclusion.

Volume S prioritizes intensity and viscera, but doesn’t sacrifice overall tonal balance too much to get it. Meanwhile the RSV mk2 seems to be going for something more like Harman’s over-ear target: bass-forward and big, but well-balanced overall.

Volume S is a more comfortable IEM for me; its longer, narrower nozzle tends to just be something that works better for my ears for long periods of time. Volume S also ends up having a tilt that is a bit more to my preference overall, veering a bit more “neutral” (even if the midrange is less neutral in isolation) and not being quite as defined by its bass.

But the big difference here is when it comes to the presentation of dynamics, where Volume S has a meaningful upside vs. the RSV mk2: Volume S is among the punchiest, most well-controlled IEMs I’ve heard when it comes to the portrayal of bass and percussion instruments, and while the RSV mk2 isn’t bad for this quality—certainly better than the DaVinci or Mega5EST—I find the Volume S to be a clear cut above when it comes to its presentation of dynamism and excitement.

While I do think the RSV mk2 probably represents the better all-rounder (again, similar to Harman’s over-ear target) I can’t help but enjoy my time spent with the Volume S more, because it just makes my music sound more vigorous and intense without making me sacrifice too much when it comes to the overall spectral balance. So Volume S gets the win from me over RSV mk2, though honestly this ended up being closer than I thought it would be.

Conclusion

Due to seeing measurements before I heard it, I won’t lie, I thought the RSV Mk2 would utterly fail to be the “reference” tool its nomenclature suggested, but it honestly got closer than I expected. It took the bones of the original RSV’s excellent midrange tuning and added a substantial enough bass lift to make it more viable for tasks other than reference listening, while still keeping it within bounds enough that I think it could work as a neutral IEM for a given listener, depending on their bass tolerance.

At times, that bass definitely does overstep its bounds, but overall I really can’t be mad at the balance here. While the value certainly isn’t the strongest, I think the RSV mk2 has enough upside versus its competition—comfort and coherence being the main two—that I think it’s an IEM that absolutely deserves to exist and slots in nicely at its price.

This is now the second Softears IEM I’ve heard, and the second Softears IEM I’ve been surprised by. Between RSV mk2 and Volume S, I feel I’m getting a handle on what Softears’ interpretation of “neutral with bass emphasis” means—tasteful, measured, and versatile across genres—and it’s an interpretation I can definitely get down with. It also really helps that this philosophy seems to entail avoiding crazy colorations in the treble.

RSV mk2 doesn’t go for the extremes in order to wow people or court audiophile gimmicks in order to bolster a fantastical narrative in the discourse, and I think it’s all the better for it. For that reason, I’m happy to recommend the RSV mk2 as a solid all-rounder, one that balances its colorations well enough that it still comes across as a set that respects the music it’s given and can balance “fun” and "neutrality" well.