So I have done some more testing on the USB port of my SU8 V2 and a small audible pop or click happens only when the bit rate changes when I switch tracks. If I go from a 96K track to a 192k it makes the popping noise before the track starts up. If I switch to another song with the same exact bit rate then no audible pop happens. I have tested the USB on my other DACs (ifi Micro iDSD BL and Schiit Jotenheim AK4490 internal DAC) and neither of those have any aubile pop at start up. I also tested using my Roon player connected directly to my Laptop's USB and through the ifi Zen Stream and still the same audible pop at startup. Also tested both using Tidal and Qobuz desktop apps and the SU8 still makes the audible pop at startup. The drop outs via USB at the beginning of a track don't happen in Tidal or Qobuz apps whether I use my laptop or through the ifi Zen Stream. The dropouts at the beginning of a track change appears to be a Roon issue and happens occasionally on both USB PC and Zen Stream. The dropout of a song doesn't always occur. If I reboot my Roon Server then the drop outs seem to go away for awhile. I'll have to watch this further. I started hearing this pop and so I did a search to see if anyone else was having this issue. I noticed this thread in ASR forum discussing this SU8 V2 popping noise. At the end of the day I can live with it, but it seams to be an issue with this particular DAC. The Coax port works great and I notice in Roon it switches tracks much faster than the USB does.Have you tried using the SU-8's USB port with another source besides the Zen Stream and Roon? Maybe a PC? Does it behave the same? It is well known that the DAC produces this fade transition when changing bettween different sample rate tracks when using USB (I have confirmed it myself) but nothing about clicks and pops. At least I've never experienced that problem
From iFi website:
"The USB ports – both input and output – support the SuperSpeed USB3.0 standard and benefit from iFi’s Active Noise Cancelling technology to remove distortion from the audio signal.
Similarly, the coaxial S/PDIF output incorporates iFi’s iPurifier signal purifying technology."
ANC for USB ports? What is that even mean? Could it be that said implementation is producing the different volume levels between outputs?
As far as the volume you make a good point about the different port implementations. The USB ports on all my other dacs also start up quieter than the coax port on my SMSL. So that looks to be due to the hardware implementation. The coax just starts at a higher volume level vs all my USB DACs.