The thing is, jitter has to be significant to hear an effect. Most is below this level and controlled by the new generation of dacs so best just to ignore any jitter angst, now a marketing tool to get listeners to feel paranoia and therefore pay sometimes ludicrous sums needlessly really.
Indeed.. async USB kills the jitter bogeyman which leaves the dreaded USB noise bogeyman.
I am using a low powered Gigabyte BRIX mini-pc running a custom ram-root linux I built that runs squeezelite and obviously usb into my DAC.
I use a HDPLEX LPS to provide the needed 12V.
The BRIX has no drives and music is sent via wifi from a fanless, noiseless server with SSD drives and LMS.
The server is at the back of my room to keep wifi strength high.
The endpoint also contains Kodi so I can play my ripped music DVD's and I use an nfs mount for Kodi to see the DVD rips stored on the server.
No need for fancy audiophile ethernet cables, routers etc or fancy femento USB cards etc.
To test USB noise, I took a pink noise WAV track, run high-pass filtering, low pass filtering and compression against it to create a test WAV file that produces the faintest 11khz signal.
I then played that test WAV via LMS and turned my volume up to "11" and what did I hear.... the faintest 11khz signal and the usual amp "rush" given the volume was at max.
By pausing and restarting the playback, I could objectively determine that there was no additional noise added via the PC playback chain.
In terms of subjective playback quality, I have benchmarked this setup against commercial products and it has never been found wanting.
Note I dont stream tidal/qobuz etc... only local playback of ripped CD's.. but LMS supports all that if I wanted to.
I am a great believer in less is more with regard to computer based playback and it boggles my mind the complexity that some computer audiophiles insist on having in their playback chain (from the router all the way to the DAC)
They obviously enjoy the tweaking side and will swear by "vails being lifted" multiple times in succession when changing PC memory, SSD drive types, finding a specific CPU clock frequency sweet spot, adding USB reclockers, noise blockers etc but surely only so many vails can be lifted in succession.
Many of the "all in one" commercial PC's have heroic levels of hardware stuck in them and from my point of view, the more "stuff" you need to power, the more noise they generate which means the probability of that noise getting into the DAC via USB increases dramatically.
If you want to upsample (as I do on my server) or convert PCM to DSD etc... do that on the server side but keep the endpoint as simple as possible.
A small, lower powered, diskless, ram-root linux end point running in a client/server topology with the endpoint running any flavour of playback software you choose (squeezelite, roon etc) will provide a high quality experience into any well engineered USB DAC.
Peter