Indeed, how the USB decoding is powered makes substantial differences to sound quality.
Note: A bit off-topic as I'm applying this to other Chord DACs not the HMS.
Thank you for sharing this snippet. I'm assuming this applies across the board to the DACs and not just the HMS. I can't recall the manufacturer # for the USB chipset ATM for my Chord DAC to compare against the HMS USB chipset manufacturer #.
I H8ed USB for Audio with a passion, but now I quite enjoy because it sounds like Toslink after powering USB decoding with Off Mains Super Capacitors (Native 5V, no regulators, 30 times lower impedance than the TT₂ Super Caps, almost zero impedance and ~6000 Farads).
Initially, I pointed the SQ improvements at powering the length of the USB cable (10M/33 Feet). By giving it Nuclear Power Plant Clean Power (Super Capacitors), I thought it smoothed out the power over a long distance. But now with your comment, I believe I'm actually directly powering the USB chipset with sufficient power so that the USB chipset can do it's job optimally with a substantial increase in SQ. It's been in the back of my head of what is going on since beginning of 2024 so it makes sense now it's about directly powering USB decoding that made substantial difference in SQ and not smoothing out power over a long distance which was my previous theory.
So Many Thanks. I was stumped why I got USB to sound so good similar to Toslink that I'm seriously considering moving away from Toslink. I like to follow Strict Sound Fundamentals so sometimes it inadvertently pays off like in this case. I didn't plan on powering USB decoding. I didn't plan on having the purest Galvanic Isolation possible. I didn't plan on unlocking the "Soundstage Depth" feature in my transportable Chord DAC. It just inadvertently happened by staying Sound Fundamentally.
I tried this recently too as I'm scaling Super Caps ATM so I had to discharge all my Super Caps to 0V. It takes a good week to discharge. The USB was not bearable in this time. Once I scaled (double the time, 1/2 the already super, super low impedance), I was back in USB heaven. My production Super Caps are usually 24/7/365 so it was a painful downtime to discharge. Progress.
I've been very Pro-Toslink my entire Chord Life, but now I'm leaning Pro-USB given I'm properly powering the USB decoding. My Chord Philosophy is less is more. Give the Chord DAC a clean low latency signal integrity with clean Off Mains power and let the Chord DAC do it's magic. Get out of it's way. I see so many that add "more" such as software upsampling that would skew the graphs below. Less is More. Keep it Clean, get out of the Chord DACs way. The wrong algorithm with software upsampling and LPS will skew the Graphs below. One by adding small errors (software upsampling) and one by noise floor modulation (LPS). It's not even a Rob Watt's DAC anymore after software upsampling, it's a hybrid with tons of small errors by not using a Chord algorithm.
That's how I was able to unlock Soundstage Depth. By keeping the graphs above super tight and super clean so no small non-linearity signal errors. When you add "More", your just tricking your own Brain. My chain is completely 100% free of the tiniest of small non-linearity signal errors. The brain adapts. It took 6 weeks to unlock Soundstage Depth, so at that time I knew small non-linearity signal errors were no longer a factor. That's why I want to stick with USB and move away from Toslink. Toslink is just a complication.
Software upsampling, LPS, etc., your just tricking your brain with a plethora of small signal errors. The brain is a quantum computer, your just confusing it so it won't compute. The trick I learned over the years is to stop confusing the Brain by eliminating small signal errors by downsizing and letting the DAC do it's job.
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Toslink for now is just more. If I can clean power the whole chain from end-2-end and keep it simple with USB, I think that is the optimal route. At least in my case, that's Plan A. With the facts and powering USB decoder is now an official thing, I think I'll stick to Plan A. Toslink will likely be a relic by the EOY. I'm the only one running Modern Toslink, not legacy Toslink too so it will be difficult to let go and move on but to stay fundamentally "Less is More" sound it should be the right thing to do.
Focus on 3/3. Once you add "More", your lucky to to get 1/3 or 2/3:
In conclusion, I get all the benefits of Toslink while maintaining all the benefits of USB. All Pros, No Cons. I also get the benefit of "Less Is More" and to keep things clean and tight. I decouple from the complication which is Toslink. A Zero variance Off Mains Chord chain. I wouldn't be able to unlock Soundstage Depth if there was a leak in the chain or if I induced small signal errors.
I'm glad too that the HMS₂ will apply across the board to other production Chord DACs and not just to the modern flagship.
EDIT: Oh, don't worry about the RF Thing-a-ma-jig. RF doesn't apply in my case because it is a certified USB Fibre Optic Cable which 100% decouples. My source is also powered by Off Mains Super Capacitors which 100% decouples so Off Mains Source doesn't apply either. Unfortunately, the Super Capacitor Supply Chain has dried up for at least the Summer, so I have to delay further projects for Summer 2025. Last time, the Supply Chain dried up for five years. Those EU Public Transportation Projects seem to be taking off as the demand is ridiculously high for Super Caps. Clean power tho is good for the environment. As a consumer, I can't compete against Industry for procuring Super Caps. But my Super Cap foundation is already solid, I just want to scale going forward. I'm looking to scale from 4 Large Super Caps to 8 Large Super Caps in 2025. Mission already accomplished by scaling 2 Large Super Caps to 4 Large Super Caps this Summer 2024. BTW, Music is super buttery smooth with this USB setup. Enough that it will melt. It's so smooth, I can loop a single track all day without flinching. What is surprising is I can play 384k over USB Fibre Optic while Toslink Fibre Optic maxes out at 192k with a Lifatec. I have yet to try 768k as it is a low priority.