I'm using USB out into a Graham Slee Majestic DAC and now looking at the specs it seems USB input is fixed at 24/48 resolution as below. I've also tried Coax output into the DAC and this does then show as 192/24 for line-in/vinyl input to the Ultra. However with extensive listening using both USB and Coax output to the DAC, the former does sound markedly smoother and cleaner so I will stick with that for all listening and have reverted to inputting vinyl/phono directly into my preamp, bypassing the WiiM for both turntables.
My Ultra listening will now remain at 24/48 regardless of source whilst using USB output to this DAC, that is what sounds most natural to me - maybe the explanation below explains this, something I looked up after back-to-back listening by the way so it seems to make sense.
From the product description:
"...The Majestic has inputs for three optical (TOSLink) sources (up to 96kHz 24 bit) and three coaxial S/PDIF sources (up to 192kHz 24 bit). USB input is suitable for CD quality FLAC and WAV files, MP3 and YouTube audio (up to 48kHz 24 bit).
.....Graham Slee chose adaptive isochronous for USB because it is time sensitive, and importantly, music is time sensitive. Asynchronous simply isn't time sensitive and data retries introduce glitches and even stop-start playback which ruins your musical interest. 48kHz, the original professional digital audio tape (DAT) sampling rate, might be classed as "old-hat" but higher resolutions suffer processing noise you won't see declared in specifications. Resampled or upsampled 96kHz & greater is only empty bit stuffing so there's nothing added to the music apart from digital artifacts that may make it sound different. It might look good on paper, but you hear with your ears, not your eyes!"
