I finally got around to testing a variety of USB and ethernet cables with the microRendu and learned some very interesting things along the way. Before I get into my findings, I continue to use the mR with the basic iFi 9V power supply that came with it while I wait for Paul Hynes to build my custom supply. The mR has been running almost continuously since I received it and it has well over 150 hours on it. During that time, it has run very reliably. As far as SQ, it is superior to anything I have heard thus far including my former CAD CAT, any Aurender (W20, N10, X100 with Ken Lau custom power supply), Auralic Aries with linear PSU and all the custom CAPS servers that have been through my system. Because an audiophile colleague, who owns a Lumin U1 as well as a modified Oppo 105D wanted to hear my mR in his system, I brought it over to his house today and now, we are both of the same opinion the mR is better than those 2 sources as well. When my better PSU comes in, I expect that delta to increase further. While my Chord DAVE DAC is immune to source jitter, it is only relatively immune to source RF and so the differences I am hearing, I believe, are due to RF that somehow pervades even the most well-intentioned music servers.
Here are my USB cable findings with the mR and my Chord DAVE:
Generic USB cable that I use for my printer ($10/2m) -- Without directly comparing it to anything, the SQ through this cable sounds very good. Only under direct comparison do you realize the sound is a bit leaner although there were not drops or stalls. There are several things that disadvantage this cable from the rest as I see it. It uses no special shielding, it has very cheap looking connectors and it is the longest cable (2 meters) of the group I tested, however, even the SQ through this cable is very passable.
TotalDac USB cable ($400/1m)
The TotalDac USB is my former reference USB cable and this cable continues to sound very good. It utilizes what I suspect to be a ferrite based RF filter. There is slightly improved tonal body and clarity compared to the generic USB cable with the mR. The difference against the generic cable is larger on the Sonicorbiter SE and Aurender N10 but still evident with the mR.
Curious USB ($340 / 0.8 meters)
The Curious USB replaced my TotalDac USB cable last fall. On my TotalDac monoblocs, the improvement was a greater sense of air around the instruments and voices. This could be gleaned as well on the Sonicorbiter and Aurender N10. On the mR, it is slightly better than the generic USB cable but against the TotalDac USB, I can hear no appreciable difference. Initially, I thought I could hear subtle differences unblinded but once blinded, I couldn't specify a preference. I could live with either.
Audience AU24 SE USB - Single Wire ($895 / 1 meter)
I am a big fan of Audience products having owned their excellent aR6-TSSOX line conditioner and AU24SE power chords over the years. This is my first experience with their new USB cable and on the Sonicorbiter SE and Aurender N10, it did not disappoint. It improved on the Curious USB in terms of soundstage and air but also clarity. On the mR, somehow its advantage disappeared. While better than the generic USB, against the TotalDac USB and Curious USB, it was almost indistinguishable.
Transparent Premium USB - ($595 / 1 meter)
This cable came to me brand new and so I gave it about 100 hours of burn-in before any critical listening. This is my first experience with the Transparent USB and on the Sonicorbiter SE and Aurender N10, it tied as my 2nd favorite cable. There seemed to be an increased weight to the presentation compared to most of the other cables with more vivid colors. The soundstage and air were superior to the Curious USB and about equal to the Audience. On the mR, it was once again superior to the generic USB cable but almost indistinguishable from the others. I am beginning to sense a trend here.
Clarity Cables "Organic" USB - ($450 / 1 meter) and "Natural" USB - ($1250 / 1 meter)
These are hand made cables by Chris (electrical engineer) and Melissa Owen, a husband and wife team based in Oklahoma. I discovered this brand at AXPONA and it is a wonderful USB cable. The only thing that differentiates the much more expensive "Natural" USB cable from the "Organic" is RF shielding. They both use a cotton primary dielectric and a teflon secondary dielectric but the "Natural" contains considerably more shielding and almost looks like a Shunyata power chord with respect to its girth. On the Sonicorbiter SE and Aurender N10, the less expensive "Organic" tied with the Transparent Premium as my 2nd favorite. "Organic" is exactly how I would describe the presentation of this cable. Not as tonally dense as the Transparent but a bit more air. The "Natural" goes even further in terms of air and space but also smoothness. It has the most dimensional presentation of all the cables here and was my favorite cable. The most expensive cable is not always the best but in this group, it turned out that the most expensive cable was the best. It also outlined just how much RF
is the problem because once again, shielding is the only thing that separates this cable from its less expensive brother. Once again, however, on the mR, the differences are more muted. Against the generic USB cable, these cables are a step above. Against the TotalDac USB, Curious, Audience and Transparent, the "Organic" becomes almost indistinguishable. The "Natural" is the only cable that I could point out reliably during blind testing because it had a touch more smoothness than the rest but I have to say this difference is very small. With the mR, is it worth its asking price. IMHO, the answer is "no."
I believe my conclusions are fairly obvious by now. USB cables don't seem to matter as much with the microRendu. Even the short USB connector that comes with the mR sounds about as good as the other USB cables. Those that have followed its development understand that John Swenson incorporated an improved version of the USB Regen into the mR and coupled with its ultra-tight regulation/isolation, its USB output appears to be incredibly clean and pure to the extent that a USB cable simply has to "do no harm" to sound good. Extra conditioning does not seem to be as necessary compared to something like the Sonicorbiter SE or Aurender N10 and while extra shielding does yield some benefits, it is not something I would pay a lot of money for. What would appear to cause harm more is not the cable metallurgy used but perhaps the quality of connectors and the cable length which could serve as an antenna to attract RF. I believe this was adequately demonstrated by the generic USB cable that had what appeared to be very low-quality connectors but was also at least 2x as long as the other USB cables used. Even with the generic USB cable, however, the SQ was very passable.
