agreed. I've never had a toslink that I thought sounded good. many high end DACs seem to be built around a preferred input and often it is USB. I haven't used Coax for a while.
USB yet again
For a few years I have had an Intona Isolator with Oyaide Continental 5S upstream and Intona Reference downstream connecting Streamer and DAC. Given the Strong benefit of filters on the upstream Ethernet connection I added a LHY Audio USB 3.0 purifier with a Grey Knights power cable. The tightening of the transfer and resultant SQ was remarkable despite having used superior cables before.
While USB remains a compromised transfer format, asynchronous USB is the only protocol synchronising the server’s and dac’s clocks unless both have master clock connections. AES/EBU may have better noise rejection but has imbedded clock signal,SPDif is outdated as well as speed constrained and I2S not standardised. Hopefully the industry comes up with a better solution. It is interesting that there seems to emerge a trend to combine server and dac: one wonders why?