Today I tested the USB input versus the AES input of the 005. First I need to share the equipment involved and the setups because that is important. In both the AES setup and the USB setup, the Grimm MU1 is the Roon server and endpoint. I only stream Tidal redbook tracks with the MU1. I use to stream Tidal "Hi-Res" but I found that the up-sampling done by the MU1 lessens the need for "Hi-Res" streaming.
AES Setup: (Grimm MU1; Shunyata Omega AES cable into the 005). With this setup, the Grimm up-samples all redbook tracks to 176.4KHz/192Khz 24bit and I can verify the up-sample on the display of the 005. The AES output of the MU1 is advertised to have "ultra low clock jitter".
USB Setup: (Grimm MU1; Schitt PYST USB cable > Uptone ISO Regen > Cardas Clear USB cable into the 005; ISO Regen is powered by a DXP-1A5DSC power supply which itself is powered by an iFi Elite power supply which is connected to the Shunyata Everest power distributor with a Shunyata Venom V14 Digital cable). With USB, there is no up-sample and again I can verify this on the display of the 005.
Critical listening is done with the Sennheiser IE900 driven by the Benchmark HPA4 headphone amp. The stock fuse was used in the 005. The 005 and the HPA are connected to the Everest via Zavfino Silver Dart Graphene power cables. The same model Zavfino XLRs connect 005 to HPA4.
I'm going to get straight to the point regarding the results. The AES Setup wins hands down! Based on my musical preferences, I don't believe I will prefer any track that is not played from the AES output of the MU1. And I have to emphasize this is NOT a knock on the USB input of the 005. I just prefer the AES optimized output of the MU1 and it has convinced me on three highly regarded DACs now that "AES" can be better than "USB" if the right streamer is utilized. The MU1 is one of a kind in what it does so I don't expect anyone to understand exactly what I'm saying and hearing until they try it in their own system.
The musical difference:
I know it's cliche but with MU1 AES, there is a veil or two that is lifted from the presentation. The details are easier to hear and there is more clarity. There is a sense of better "sound separation" and I can hear sound nuances easier. The music sounded slightly louder in a good way. A component change can cause music to sound louder if it's amplifying perceived noise/distortion and this is not good. But I get the sense the MU1 AES is helping amplify the music itself so it's desired greater loudness. One of the best things I loved to hear with the 005 was the way percussive sounds or stick type hits would present themselves. These types of sounds were crisp and strong and had great texture and pop. Doing this experiment, I realized how much the MU1 AES actually played a role in making this sound. That is to say with the USB setup, this characteristic was lessened.
Based on past similar experiments involving the MU1, I knew this was not a fair test for USB and today's experiment just reaffirms why I moved on from my USB optimized chain. I'm not saying USB is bad because it is definitely not but the MU1 AES is just better in my experience.