Well, hear.
I also use Roon and have a SN3 and nDAC (with small Proac speakers)
For several years, I fiddled around with several USB>SPDIF converters with variable (and sometimes unsuccessful) results but I eventually switched to using a network streamer instead, which is what Roon themselves recommend.
For several years I used a Raspberry Pi + Hi-Fi Berry SPDIF add-on card which worked absolutely perfectly and sounded great.
I eventually moved the Rpi to my study system and replaced it with an iFi Audio ZEN Stream Wi-Fi Audio Transport which connects to the nDAC via SPDIF and sounds fantastic plus adds Spotify, AirPlay and Chromecast streaming smarts.
I’d recommend you give up on USB>SPDIF convertor path and put your funds towards a similar network streaming solution.
For clarity, the industry standard specs state that 192Khz is the max sample rate for SPDIF and 96Khz for Toslink (it’s not a nDAC limitation)
I will try to upscale from roon and see what happens.
likely not much
Seems like i’m walking a path you walked in the past, thanks for the advice, I’ll give it serious thought, plus, second hand the zen stream is within budget.
I did not know roon recommends using a streamer as an endpoint
Toslink 96Khz max, will be with a poor quality 15m cable.
A good quality 0.75m Toslink cable will work at 192Khz.
I use a VDH optocoupler between a Primare NP5 and ndac at 192Khz without a problem.
I used a 2011 Mac mini for a good while via toslink and Audirvāna to a Naim DAC. It was very good (252/300) and a long way ahead of my CDX2.
When the Mac died I had to move to spdif usb and it was a big step back, only solved by getting a streamer, which enabled me to use the Mac completely away fro:the hi fi.
A streaming device to the DAC is the way to go.