RD-X - rhythmdevils modded LCD-X reviews and measurements

I spent about a week with the RD-Xs and enjoyed my time with them very much. Regardless of which amp I tried these with they had impressive resolution, good tonal balance across the FR, and a delicate openness to the sound that was very addictive. I like @purr1n's description of their tonal signature as an "HD650 with fixed bass." That works for me.

My favorite aspect was the resolution. A good step up from HD650 levels. They do not reach Utopia levels – this was most clear to me in the treble/air regions where the RD-Xs cannot resolve the level of detail that the Utopia can – but this is not a knock. Given their price, the RD-X is remarkably resolving.

They do have a couple quirks. I don’t want to call these “cons” because depending on personal preference, these could easily be pros.

• There is a diffuse, shimmery quality to some of the midrange and treble. This kind of thing is hard for me to pin down. Instruments and vocals sound realistic with correct timbre; they are just rendered in a more diffuse, airy way than I am used to hearing from dynamics which render sound with a more solid quality. Is this rendering style inherent to the planar diaphragm? Or is it something that @rhythmdevis is shooting for or enhancing with mods? It is often beautiful and can be really involving with certain tracks.
• Instruments and sounds occupy distinct space, but compared to something like the Utopia where the soundstage is more of a tight sphere around your head, the RD-X stage was stretched out wide. Picture two cone-shaped party hats, worn over each ear pointed straight out to the sides of your head. There is still three-dimensionality, It’s just concentrated to the left and right.

For amp pairings, I liked the EC Studio B most. It was the most tonally balanced pairing, and the three-dimensional abilities of the Studio B helped enhance what the RD-X could do.

The DSHA-3FN was also very good. A more neutral pairing overall which really excelled in speed/responsiveness.

Pietus Maximus was also enjoyable. The amp’s resolution and finesse was not wasted on the RD-X, although the bass lost a bit of grip and was more rounded than with the DSHA.

I also tried them briefly with the EC Black Widow 2, which ranked last on my list of amps. Depending on your preferences, one of the drawbacks of the BW2 is a disconnect between its “organic” lows and the more articulate highs. The RD-Xs resolving ability and inherent speed made this disconnect more audible and apparent than I’d heard before with other headphones.

Unfortunately, I have not heard the stock LCD-Xs and can't comment on how different the RD-Xs are.

Thank you @rhythmdevils for the opportunity to hear them and congrats on your creation!

 

It’s not every day you get to experience different iterations of the same headphone/speaker design to do a side-by-side comparison, let alone considerable modifications to an existing (and very successful) product. Listening to the RD-X was an interesting and informative experience, so I want to first thank @rhythmdevils for allowing me to spend some time with these as part of the loaner tour.




As a quick background, I should explain my personal interest and rationale for wanting to listen to the RD-X. Having owned a stock set of LCD-X (2021), until late*, I’ve had to utilize PEQ via my laptop to optimize my listening experience with these headphones. In stock form, my LCD-X’s frequency response has a decent dip in the 4kHz range, which had collapsed the center image’s spatial presentation and soundstage depth, while also causing a bit of wonkiness to vocals. Applying Oratory1990’s LCD-X PEQ profile helped considerably in restoring that upper midrange response to a more natural level. While I do reduce the bass shelf a bit and only apply 4dB of peak filter around 4kHz (vs. Oratory’s 6-7dB peak), I do like the overall change that his profile offers.



*Since swapping my headphone amp from the Lyr 3 to the DIY ACP+, the impact/need for the PEQ application has greatly reduced to the point of being almost perfectly content using my CD player directly without any PEQ. Go figure.



My interest was piqued to see how the RD-X sounded vs. the stock LCD-X as well as vs. the PEQ-applied LCD-X, and see how much and what type of difference there would be.

Two things jumped out at me as soon as I went from my LCD-X to the RD-X: stage/image presentation and volume. The RD-X must be more efficient, because without touching the volume knob, the perceived volume jumped by several dB. This was something I needed to adjust for in the DSP so that I could do a moderately proper comparison. So I added a PEQ tick for -6dB in volume when switching over to the RD-X. That seemed to level the playing field (sorry, I don’t have the equipment to measure a level match).

As for the stage/image presentation, it was significantly more forward and had a very speaker-like presentation – kind of like a perfectly implemented crossfeed effect. This was the definitive WOW factor for the RD-X. There was a very solid total image spanning a nicely wide soundstage, and it all had a rich and cohesive quality to it. Everything is just right there – and to me, this was almost to a fault, as it felt like all the sonic information was being crammed into my frontal lobe. It’s a bit intense, very intimate, projecting all the texture and detail at you all at once. This is a very resolving headphone in combination with the stage presentation.

Compared to the stock LCD-X, which is a more laid-back presentation with a darker overall tonality and balance, the RD-X has a more vivid and defined image – by a matter of degrees here, but it’s still very noticeable. I tried to illustrate below the difference in how the image and soundstage is presented between the two (from my perspective), wherein the LCD-X has the sense of a taller and deeper overall stage, but a slightly more diffuse image within it. And the RD-X has a sense of a more vertically condensed overall stage, with a more forward and concise image that spans across it. The biggest difference to me was how the stock LCD-X does exhibit a 3-blob effect, which I thought it did not since the day I originally auditioned them several years ago. It just so happens that the mods in the RD-X make that much more apparent.



The other differences I could pick up on were, as many others have mentioned, the bass roll off in the RD-X (but very tight and dynamic), which definitely made itself evident in tracks that deliver hefty bass rumble. Listening to the Man of Steel soundtrack, Hans Zimmer has that knack for robust bass rumble throughout his work, and while the LCD-X delivered that rumble in spades, the RD-X definitely did not. It’s for sure a trade-off between these two. The RD-X offers all the bass impact you could want, and maybe a touch more than the LCD-X, but you lose some of that low end extension and gravity to the response. This might also contribute to the sense of the condensed stage height.

Midrange response was very similar, where the RD-X carries a bit of midbass warmth and body that the LCD-X doesn’t display. This warmth also grants some richness to the mix, which was very welcome. And of course, the upper midrange was demonstrably better with the RD-X vs. the stock LCD-X (especially when EQ was not applied). Adding EQ levels the playing field much more, however.

Where the RD-X did not align with my preferences was in the treble response. Comparatively, where the LCD-X has a more relaxed and darker response, the RD-X is very different to my ears, as it is much more forward, pronounced, and brighter. Keep in mind, I am extremely treble sensitive, and this was paired with the solid-state ACP+. Here’s a grain of salt. I guess I just prefer a less prominent treble response, so for me, it didn’t work well with several genres (most of my heavier stuff like Tool, Opeth, etc.). With that music, I got a bit more splash with cymbals and brightness with guitars. Maybe a really good tube amp would mellow that out to my liking.

In the end, both have incredible tonal/timbral qualities, they just present them differently. In terms of macro and micro-detail, they are very similar as well, you just get a bit more of that in the RD-X’s more forward presentation and detail is more readily discernible. It’s all still there in the LCD-X, but you need to peer into the mix a bit more to pick up on it. I think overall I preferred this – sometimes the RD-X was too much of a good thing with certain genres. Going back and forth between the two, which one I preferred seemed to be very much genre (and even track) dependent. Once I would have one set on my head for a few minutes and my brain adjusted, I basically forgot about the other – they both do things so well, just differently.

A last note on comfort: the pads on the RD-X are definitely lighter, more pillowy, and have less clamp force. However, I think I prefer the angled stock pads and the overall feel of them, despite inducing more clamp force. Maybe I’m a glutton for punishment – but I preferred the stock LCD-X pads.


To conclude, I walked away from this comparison feeling that overall system synergy would be even more paramount for the RD-X than maybe even with the stock LCD-X. I can imagine a really quality tube amp paired with these (as others here have obviously used) would balance out some of the areas that I felt may have been a bit forward or lacking. I’m glad I have the ACP+, because I don’t think I would have gotten as good of insight into the differences between these two if I still only had my Lyr 3. The RD-X is a really engaging headphone, and I loved the speaker-like presentation they offered. If I did own them, I do feel like I’d need to go down the gear synergy rabbit hole, or at least still apply some EQ to taste. So for now, I’ll live contently with the stock LCD-X – but the RD-X has some really strong improvements and advantages, and are absolutely worth consideration for anyone looking for a hot-rodded version of the already-stellar LCD-X.

 

RD-X Impressions
I’d like to thank @rhythmdevils for kindly lending me his RD-X headphones. I had the privilege of hearing these headphones at the same time that he also lent me his RD-4s (inc. the RD-4z) and not long after I got to hear his RD-Rs. I’ve posted impressions of these other RD-modded Audezes here (for the 4) and here (for the R).

The RD-X share the same house tuning as rhythmdevils’ other modded Audezes, which is to say a neutral sound signature that’s got a slight, inner warmth to it. This is a neutral sound done right: it’s not in the least bit clinical or dull. While sharing the same tuning, the RD-X differ slightly in some characteristics from the RD-4s and RD-Rs, for reasons, I suppose, that have to do with the qualities of the drivers. In several specific ways, like slam, punch, and macrodynamic strength, the RD-X is better than its pricier siblings, although it is less resolving, as one might expect from one of Audeze’s mid-priced headphones vs its totl ones. These are easily one of the best pairs of headphones, for my preferences, in its price range. I preferred it to the Focal Clear and liked it better than the Auteur Classic, although I fully appreciate the Auteur’s many qualities.

I’ve not heard the stock versions of the LCD-X (before and after the 2021 revision) for a while, and never outside the confines of CanJam, so I can’t offer a direct comparison to the stock model. But on the basis of RD’s mods of the other Audezes, and based on the X’s similarity to these other modded ones, I’d venture that they’re likely to be a big improvement: the RD-4 and -R, for instance, have a more even, coherent, and better balanced tuning, superior resolution, and a much more open, airy, and spacious presentation than their stock counterparts, and I hear these same qualities with the RD-X.


Preferences and caveats
I’m in my mid-40s and can’t hear much above 14 kHz. I’m sensitive to too much emphasis in the upper-mids and lower-treble as well as fussier than most about wanting headphones to be free of congestion, veil, and a closed-in headstage. Excess warmth bothers me, a lack of treble air is suffocating, and I lean more towards the HD 600 than the 650.


Setup
Mac Mini with Roon with Qobuz and FLAC/ALAC files via Unison USB -> Yggdrasil A2 balanced or balanced to Jensen PO-2XR converting to SE -> various amps: Monoprice Cavalli Liquid Gold X, which rhythmdevils used to tune them, DNA Stratus, and, to a less extent, with a Ragnarok v. 1.5, Mjolnir 2 with WE 396A tubes, Violectric V281 and, briefly, a Holo Audio Bliss.


Tonal signature of the LCD-X and rhythmdevils’ other modded Audezes
Since I’ve heard several of rhythmdevils’ modded headphones, I’ll copy and paste some of my impressions of the house sound since they also apply to the RD-X. No aspect of the frequency response seems to predominate. In this sense, I’d call all his headphones neutral, although I recognize that there’s no consensus as to what “neutral” means and that it’s a relative term. In this case, I use “neutral” to mean several things: the tuning is even and balanced; no one region of the frequency response seems recessed or overemphasized. If anything, I’d say the tuning is mid-centric. The mids are slightly forward, just enough that vocals stand out nicely and are wonderful, but not so much that lower and upper registers are set back in relation to them. If you listen either for the bass or treble, both are also done exceptionally well. As with the other RD-headphones, vocals are glorious, being presented prominently but not in any way to strident, shouty, or sibilant excess.

The bass goes down deeply into the sub-bass region and produces plenty of satisfying rumble. The entire bass region is well balanced, with the mid-bass textures and punch working nicely with the sub-bass depth. This isn’t the kind of bass that’s intrusive when the music doesn’t call for it; you can listen to orchestral works without the low end being exaggerated. At the other end of the spectrum, the treble is lovely and clear and well extended without being too forward or bright. And there’s lots of sparkle and top-end air. Whitney’s headphones tend to have the best treble I’ve encountered. It has a pleasing, lucid quality.



Distinctive qualities of the RD-X’s sound
Beyond tuning, the sound of the RD headphones is very slightly wet; these aren’t dry sounding headphones. The RD-X isn’t quite as liquid as the RD-4 or the RD-Rs, though.

The RD-X have less note weight—or tonal density—than the RD-4s, although they still have a substantial, weighty sound, more like that of the Clear and Auteur than the HifiMen HE1000 models. Neither the RD-4s nor the RD-X sound overly thick or ponderous or sluggish. They still have a clean sound, excellent timbre, and enough edge to transient attacks as to be lively and energetic. The RD-X have a lighter, snappier, more impactful sound that’s really appealing.

Where the RD-X stands out most conspicuously from the other RD-Audezes is in their slam and percussiveness. The slam is a function of the bass presentation, of course, and it hits hard. The bass goes deep and is robust. It has a boomy quality with some songs, which isn’t to say it’s loose or poorly controlled—it’s quite the opposite—but rather to say that it’s got lots of air and space and heft to it. The X’s bass is a bit less authoritative than that of the LCD-4/RD-4, but it’s still outstanding.

What makes the slam so good, I suspect, is the overall percussiveness of the driver and the damping system. Throughout the frequency range, there’s a great deal of impact and punch. I found myself listening more attentively to drums because they sound so damn good. The RD-X’s punchiness also stems from the excellent macrodynamic contrast of the headphones, which is greater than with the LCD-4 or the RD-modded equivalents. We’re not quite at Abyss 1266 levels of slam and impact, but not far off.

The leading edges of notes also have a good amount of incisiveness to them. They’re snappy, but not quite as snappy as the RD-R (from memory) or the RD-4z. The staging is nice and open and spacious, without being dramatically so—the 4z is better at this—and there’s no congestion whatsoever. Layering and separation are excellent, perhaps among the best in sub-$1.5k headphones (and better than many pricier ones), although imaging, while solid, isn’t quite as laser focused as something like the Focal Clear (again, from memory). The imaging is precise enough, though.

Taken together, all these qualities make the RD-X a fun pair of headphones, ones that are also nicely tuned and have lovely timbre.


Timbre
Pianos sound convincing, in large part thanks to the neutral tuning. They’re nicely percussive, too.

String instruments have a nice sharp bite to them but aren’t screechy, although the violin had a bit of an edge to it, which is probably intrinsic either to the instrument or the recording (Shostakovich’s String Quartet 8 with the Fitzwilliam Quartet). String instruments keep their sweetness, and the treble clarity and air means that harmonics from acoustic guitars sound great. I particularly enjoyed the strong textures of instruments, which had a bit of grittiness to their reverberations. While there’s a bit of blurring of individual instruments in the quartet, the cello sounds lovely and rich and distinctive, with its woody, hollow-bodied sound coming across beautifully.

The strong tactile quality to string instruments is also there with brass. Trumpets and horns have great blart, blare, and crackle. Trumpets can be a bit piercing, much as in real life. Woodwind instruments like the alto sax also sound great – not too sharp or strident (which sometimes detracts from some headphones’ rendering of jazz recordings for me).

In keeping with the excellent treble and snappy transients, cymbals also sound great. I use Cannonball Adderley’s jazz piece Autumn Leaves to listen to the quality of brushstrokes on cymbals, which with the wrong gear sound mushy and shushy and not as clearly articulated individual strokes. The RD-X does a great job at differentiating these brushstrokes, better even than the RD-4 mk II, although not the RD-4z, which has faster transients.


Conclusions
I’m sorry for not offering direct A/B comparisons with other headphones in the same price range. I’ve mentioned the Clear and the Auteur Classic, and I prefer the RD-X to both, but I’ll refrain from saying anything more because I don’t trust my auditory memory. I’ll also post some further comparisons with the RD-4 mk II over in the other thread for rhythmdevils’ modded headphones.

The RD-X are excellent headphones. They’re neutral, not too warm or dry or wet, neither soggy nor parched. Their sound is well balanced. The bass is tight but nicely textured and gives the pleasing sense of moving air. The mids are even and smooth and forward enough to make vocals sound lovely and clear. And the treble has a lovely clarity and sweetness, with plenty of air and the ability to do justice to the overtones of acoustic guitars. There’s lovely sparkle. There’s lots of space and air for music to breathe openly and expansively, without being conspicuously large or diffuse in its staging. And there’s lots of awesome impact, slam, and macrodynamic strength. These are fun but also nicely tuned headphones. They may not be as resolving as the other RD-Audezes, but the resolution is entirely in keeping with, if not better, the Auteur Classic and Clear. These are probably my favorite sub-$2k headphones.