I’ve written quite a bit about the sonic benefits of various USB conditioners. The UpTone Audio USB REGEN was my first USB conditioner and I was blown away by its performance. It probably had the most natural timbre and tone out of the ones I’ve tested but came off a bit flat and fuzzy around the edges. Unfortunately, I didn’t get a chance to evaluate the USB REGEN with a better power supply which could’ve opened and tightened up the sound. In any case, I have no qualms in recommending the USB REGEN as I found it to be musical and affordable. So when the ISO REGEN was announced, I couldn’t wait to get my hands on one.

Before diving into this review, I wanted to make a comment about measurements. We all have our biases in audio and different hearing sensitivities. I used to take the scientific approach and found solace in the quantitative. This, for the most part, became a waste of time. No matter what kind of engineering was involved or how the device measured, if it sounds like crap to my ears, what’s the point? I’m not saying measurements can’t provide insight into how a component may sound because they obviously grant us a useful reference point. I just believe there are some things about an individuals’ preference for musical enjoyment that can’t be determined from charts and graphs. In fact, I think it’s better to listen, figure out what kind of sound you like, then take measurements. With these measurements, you could then filter components more effectively. You’ll also get a more intuitive and tangible idea of what you’re looking for.

Now back to the ISO REGEN. Given the $325 price point, I predicted the ISO REGEN will be a slightly better USB REGEN with improved layering and delineation. If that were the case, it would be my top recommendation for a USB conditioner. Given UpTone Audio’s reputation for providing high-end sound without a high price tag, I outright purchased the ISO REGEN along with four UltraCap LPS-1 linear power supplies.

Here’s what Alex Crespi had to say about the ISO REGEN:

Frankly, the galvanic isolation is nice (especially when powered by an UltraCap LPS-1), but the rest of the tremendous enhancements we made to the rest of the REGEN (Crystek CCHD-575 clock, USB3.0 hub chip with the best signal integrity John has ever measured, and five of the world’s ultra-lowest noise packaged linear regulators–the LT3042) far exceed the SQ benefit brought by the isolator.

The impressive design of the ISO REGEN was quite thorough. If you want more technical details please refer to UpTone’s ISO REGEN product page and their very well written white paper. I’ll be focusing on performance.

Setup & Preparation

  • I used both custom Omega Compact Alnicos speakers and Abyss / HE-1000 V2 headphones to validate the performance characteristics.
  • DACs used were the Chord DAVE and Chord Hugo.
  • Direct connection from a late 2013 Macbook Pro and SOtM sMS-200 with a Danacable USB cable.
  • A SOtM stack (tx-USBultra + sMS-200 + clocked switch) with two Danacable USB cables (I’ve found these cables to sound the most natural. Ask for a length below 3 feet to avoid impedance issues with the tX and ISO REGEN).
  • The UpTone UltraCap LPS-1 power supply is one of the gems in audiophile land and probably the best linear power supply under $1,000. I would swap out the DC cable that comes with the LPS-1 with a UPOCC copper or silver DC cable ($100) from Zenwave Audio. It’s the best copper DC cable I’ve heard so far (email: If you prefer a silkier sound, the Sonore DC-4 is also a great choice.
  • At the DAC, the UpTone Audio’s USPCB USB adapter was used. This is supposedly better than using any USB cable and comes free with the ISO REGEN purchase.
  • Make sure you have the ISO REGEN switched to the “1” position and not the “On” position. This will activate the galvanic isolation. The “On” position is for debugging purposes only.
  • The provided USPCB USB adapter could be a bit slanted so it may be easier to insert the adapter into your DAC first before attaching the ISO REGEN.
  • If you’re swapping out USB cables for testing, you may need to unplug and replug the power on the ISO REGEN to get it to be redetected.
  • I used a few Gingko ARCHs to support the ISO REGEN at the Chord DAVE. It keeps it from bending at the port. If you need flexibility in your vibration isolation, these ARCHs come in so handy. I also have them placed under my source components. You’re able to adjust the sound by stacking more or less of them.
  • Some may consider using a battery pack or switching power supply for the ISO REGEN. I advise against it for the best sound quality. FWIW, using a SOtM mBPS-d2s provided more warmth but the soundstage was flatter and everything was fuzzier around the edges. With the UltraCap LPS-1, everything opens up but becomes thinner. My preference was for the LPS-1.
  • Don’t use a cheap Y-splitter power cable, especially the one from Amazon. It will degrade your sound quite harshly. You’ll notice it.
  • If you’re attaching the ISO REGEN to the Chord DAVE be very careful not to put pressure on the USB port of the DAVE (especially if you’re using the RCA jacks to power speakers). You’ll have to elevate the DAVE and use some foam. I actually had to get my USB port repaired.


The performance of the ISO REGEN is also determined by the power supply and DC cable used. Your results may vary. All of my components (outside of my Roon server) is powered by an UltraCap LPS-1 and Zenwave Audio UPOCC copper cable.

Direct Macbook Pro and SOtM sMS-200

Direct from computer or streamer will be the most common configuration when using the Uptone Audio ISO REGEN. I’m just going to cut to the chase: The ISO REGEN will elevate your system to heights you never thought possible. I didn’t have to go through more than a single recording to realize this.

Going straight to DAC without having the ISO REGEN in place resulted in a very thin and piecewise sound (on both the Macbook and sMS-200). It’s likened to a Pixar movie with only the geometric models and no shading or texturing. You’ll be missing all of the elements that make music fun, colorful, and emotive. The sonic variance is quite significant.

vs. Wyred 4 Sound Recovery / SOtM tX-USBultra

Many were wondering how the ISO REGEN stacks up again the competition. These are my two reference USB conditioners. These impressions are in my “raw notes” format and were taken as I was listening. It’s a lot so feel free to skip to the summary at the end of this section.

My Father’s Eyes [Take 2] – Eric Clapton (44/16)

vs. W4S Recovery

  • Didn’t take much A/B to find that the ISO Regen is superior in every way. The performance delta was enormous and convinced me I didn’t really need to compare the two any longer.
    • Much more open and dynamic
    • Better delineation around instruments and voices
    • More sparkle and a darker background
    • Much more engaging and euphoric
    • Amazing transparency and insight into the music
    • Much much higher resolution. You’ll hear every nuance of the recording without it being sterile.

vs. tX-USBultra

  • tX-USBultra
    • is even more detailed
    • has more clarity and slightly less veiled.
    • has better extension on both ends
    • has more dimension to the music, more nuanced, more real.
    • Warmer with a richer midrange
    • Fantastic low-end weight and presence
    • Relentlessly accurate timbre and tone

Candela (Live) – Buena Vista Social Club (44/16)

vs. W4S Recovery

  • The W4S Recovery sounds pretty bad. Super flat, no textures on vocals, guitars, or drums.
  • As far as performance, the ISO REGEN is in a different universe.
  • W4S lacks air and delineation completely. The best thing it has going for it is it’s natural tone and timbre.
  • W4S is very dull sounding while the IR is accurate, natural, and rounded.
  • The differences are so great, I don’t know if this is a fair comparison.
  • The W4S sounds low-res, flat, and fuzzy vs the ISO REGEN.
  • The ISO REGEN conveys a sense of space in a very natural way.

Machete – Buckethead (44/16)

vs. W4S Recovery

  • W4S doesn’t sound like music. Just sounds muffled. Talk about kicking them while they’re already down.
  • The ISO REGEN has so much texture, crunch, and air in comparison.
  • This track could be a bit convoluted but the ISO REGEN is able to maintain grip and deliver all components effortlessly.
  • The ISO REGEN is very musical and airy. Fantastic layering and sonic separation across the board.

Diablo Rojo – Rodrigo y Gabriela (44/24)

vs. W4S Recovery

  • The W4S sounds bloated, lacks sparkle, and refinement.
  • ISO REGEN has all the bells & whistles. The slam, snap, and rumble.
  • ISO REGEN is so much more dimensional and palpable. It’s an accurate reproduction of intent.

Three to Get Ready – Dave Brubeck Quartet (44/16)

vs. W4S Recovery

  • W4S is much flatter and fuzzier than the ISO REGEN
  • W4S doesn’t have close to the amount of air or clarity
  • Dynamics are non-existent with the W4S while the ISO REGEN is able to convey quick transient attack and decays with ease and precision
  • Bass plucks are a smeared mess on the W4S while on the ISO REGEN it’s crisp and clear
  • Trumpets sound a bit congested and lack micro-details. ISO REGEN just sounds unconstricted.
  • The drum hits get lost with the other instruments on the W4S. ISO REGEN delineates all the players very well.

You Fckn Did It (Live) – Jason Mraz & Noel Rivera (44/16)

vs. W4S Recovery

  • W4S makes it sound like the performers were performing in a stuffy, hot, and sticky room.
  • W4S is a smeared mess. ISO REGEN has just the right amount of depth and detail to be musically enjoyable.

Contact – Daft Punk (88/24)

vs. W4S Recovery

  • Cymbals sound a bit tinny with the W4S.
  • W4S is void of any atmospherics. ISO REGEN is infinitely open, frees the entire spectrum.
  • ISO REGEN very insightful sound. Much deeper and wider soundstage. The W4S has a smaller image and a tighter space.
  • ISO REGEN has a billion times more resolution than the W4S.
  • Once again, the W4S isn’t compelling in comparison. Oddly, I thought it was a really fun USB conditioner but in comparison to the ISO REGEN, it sounds dull and muted.

Overture (Live in Hong Kong) – Alan Tam (44/16)

vs. SOtM tX-USBultra

  • tX
    • is more articulate and spacious and controlled
    • has more depth and a larger soundstage
    • sounds a bit thin and less euphoric than the ISO REGEN
    • resolves every tiny detail in the music. Those plucks on the electric guitar are better delineated.
    • has tighter bass. There’s no bleeding. Even the female grunts towards the end of the track have more definition and shape.
    • has much more resolution. You could literally visualize the the sticks smacking and gracing the drums.
    • presents percussions with authoritative slam, punch, and definition.
    • sounds real besides a bit lean.
  • ISO REGEN has much more bass weight and definition. It has a more romantic sound and admittedly more fun.
  • ISO REGEN has a cozier sound while the tX reveals the acoustic space much better.

(Sittin’ On) The Dock of the Bay – Sara Bareilles (44/16)

vs. SOtM tX-USBultra

  • The tX sounds a bit sterile vs the ISO REGEN
  • The ISO REGEN is more melodic, warmer. tX has more spatial cues.
  • The tX is has much more resolution and better timing. The reverbs don’t go to the back of venue on the ISO REGEN.
  • The ISO REGEN’s midrange sounds more well-placed while the tX sounds a bit recessed.
  • I enjoy the tonal density of the ISO REGEN more than the tX.
  • tX has more implication to the music. It’s cleaner and more coherent.
  • tX flows more granularly at higher resolutions. This provides an eerie and realistic sound.

Jazz Variants – O-Zone Percussion Group (44/16)

vs. SOtM tX-USBultra

  • The tX atmospherically takes you closer to the live performance but is lacking in midrange mass.
  • The ISO REGEN gives the sound great fill and volume along with the proper textures.
  • ISO REGEN has a ton of impact and dynamics. Lots of mass and musicality. Great tone.

Summary of Comparisons

Wyred 4 Sound Recovery

  • Although the W4S Recovery improves the sound significantly, the ISO REGEN takes it up to a whole new ballgame. The disparity was high and the Recovery was simply outclassed.
  • The W4S Recovery just sounds congested, overly forward, and restrained. Given the fact I actually liked the Recovery and now found it to be borderline unacceptable…speaks on just how good the ISO REGEN is.
  • The W4S Recovery does perform decently with studio music but loses coherence and air with live recordings.

SOtM tX-USBultra

  • Given the respective price points, the sonic variance wasn’t as large as I thought it would be.
  • The tX will startle and surprise me but the ISO REGEN will provide a more relax and enjoyable listening session.
  • The tX is more startling but I found the ISO REGEN to be more engaging. The thinner character of the tX is noticeable in this comparison. Piano notes have more weight and density on the ISO REGEN than the tX.
  • The tX is more transparent, clean, and detailed. You hear every nuance and obtain greater immediacy but it’s not necessarily musical. It lacks a bit of low-end mass and a layer of warmth to be fun. The ISO REGEN has less air but is musical.
  • The beauty of the tX-USBultra is its ability to provide realism via its super clock. The level of sonic granularity and spatial resolution (better decay and much longer reverb tails) is something to be heard. The ISO REGEN doesn’t provide the same level of realism or layering but offers more meat on the bones. Because of this, I actually had more fun listening to the ISO REGEN for the more bass-heavy tracks.

SOtM Stack

Since the stack includes the SOtM tX-USBultra, the idea is to find out what improvements, if any, could be obtained by stacking the ISO REGEN before or after the tX.

ISO REGEN before the tX

  • Something didn’t sound right with this configuration. At times I felt it caused a little bit of degradation in the sound. Other times it came off too thin and excited.
  • UPDATE (7/12/2017): After some readers have commented on getting better fidelity in this configuration, I retested and these were my findings:
    • This configuration provides a much more expansive sound, better resolution, much better layering, and is definitely quieter. There’s undeniably more air, realism (from a detail standpoint), and spaciousness. It’s fantastic for orchestral music.
    • The tradeoff is a thinner sound. Voices and instruments (especially piano) don’t have enough tonal mass for my palate. Having the ISO REGEN after the tX provided much more meat around the bones at the (not insignificant) expense of soundstage and resolution. The image shrinks quite a bit and there’s a loss of dynamic shine. However, that’s a tradeoff I’m winning to make to obtain a warmer sound. Going in one direction usually takes away from the other. Lucky for us, we have a choice and it doesn’t cost a dime more 🙂
  • UPDATE (8/19/2017): After swapping out the power supply on my BRIX server with a SOtM sPS-500, the ISO REGEN sounded bettter before the tX.

ISO REGEN after the tX

  • Now, this is the jackpot combination. The tX and ISO REGEN sound good on their own but this combination is an absolute godsend. The ISO REGEN not only provides the much-needed midrange density on the SOtM stack but also improved depth and tonal balance. The dynamic envelope of percussion, brass, woodwinds, and strings are unadulterated and pure. There’s a small loss of resolution and air but the rendered musicality is undeniable and addictive.
  • The combination of the two is a force to be reckoned with. It doesn’t have the meatiness as with just the standalone ISO REGEN but gives the tX just the right amount of tonal density to satisfy most palates. A tiny bit of resolution and air is traded but it’s well worth the exchange. I could use a bit more warmth but I can’t complain.
  • Without the ISO REGEN, the sound just isn’t as epic. The combination affords you some insane realism. Spatial cues, decay, and ambiance galore. It adds so much more depth and dimension to the music. The gestalt of the tX and ISO REGEN is an otherworldly combination.
  • I wasn’t thinking about keeping the ISO REGEN as I presumed the tX-USBultra will be sufficient. Now the ISO REGEN has become an integral part of my system.


Without the UpTone Audio ISO REGEN in place, recordings were flat, lean, sterile, and not very involving. The ISO REGEN applies a nice layer of rich texture, warmth, and roundness to the music. This is especially in the presence region where it matters the most. The bass region is not only prominent and weighty, it’s also very detailed. The ISO REGEN also has the capability of layering and separating all components of the music in a very coherent, smooth, and natural way. Voices and instruments are better localized and well-focused with the proper timbre. This level of authenticity and nuance conveys an incredible listening experience.

Other USB conditioners seem to aim for a specific signature. The ISO REGEN, on the other hand, is effortless, honest, and accurate. I don’t sense any coloration, just musicality. It breathes life into the music without overdoing it. There’s really something compelling about the ISO REGEN, even over the venerable SOtM tX-USBultra. Although the tX-USBultra imparts a more realistic fabric of sound, the ISO REGEN was just really fun and less fatiguing to listen to. It also doesn’t require two USB cables. As mentioned, the combination of the two is so good it should be a sin. The ISO REGEN certainly blows the other USB conditioners I’ve tested out of the water and rendered them obsolete. A new bar has been set.

I knew within a few minutes of listening, the ISO REGEN had to be a part of my system. It was the proverbial cherry on top and the final piece of the puzzle for what I would consider being my end-game system. This SOtM stack (which I consider to be the most important component in my system) was a bit lean and I’ve been chasing warmth with cables. Without the ISO REGEN I feel like it would be impossible to obtain this level of fidelity and realism, no matter how much tuning I do. The ISO REGEN supplied just the perfect amount of midrange density and I’ve never heard my system sound this “right.”

So it turns out the ISO REGEN wasn’t a slightly better USB REGEN. It’s clearly in a different league. The galvanic isolation the ISO REGEN provides is the real deal. If it were me, I would get the ISO REGEN to start and combine the “SOtM Stack” when you’re ready for the next level. I really admire UpTone Audio’s John Swenson and Alex Crespi’s drive to continually innovate and improve on uncompromising and affordable products. If you have a USB DAC, you owe it to yourself to give the UpTone Audio ISO REGEN ($325) a shot. I would opt for the discounted bundle with the UltraCap LPS-1 ($655) and tack on a Zenwave Audio copper DC cable. You have 30 days but you’ll only need a few minutes to realize just how much musicality you were missing from your favorite recordings.