I am running a basic NUC using JRiver... Is there any sonic advantage to using in place of the NUC a dedicated computer made for it's quiet operating. and high quality signal? Seems to me that the sound quality of such a unit is not critical since the Optical Rendu does the heavy lifting. Am I right?
I never noticed a sound quality difference between using a low and high power music server when using JRiver.
I have noticed a huge sound quality difference between JRiver and HQPlayer. I used JRiver for 10 years with a low powered music server. When that server died I built a higher powered fanless server that uses an Intel i7-9700 CPU. The new server enabled using HQPlayer which is how I discovered that JRiver has a happy little mid-bass bump which makes all music a little phat, which everyone likes.
I use the latest
HQPlayer 4 Desktop: 4.21.1. The filter and upsampling engine used depends on the CPU. The i7-9700 can upsample 44.1 kHz to 1.5MHz and DSD256 all day but is too weak to do DSD512. JRiver now sounds muddy in comparison.
Have you tried the opticalRendu Mode #4 - HQ Player NAA Output? This output utilizes streams from Signalyst's HQ Player running on your computer. Digital signal processing is performed by HQ Player and then asynchronously streamed to the Network Audio Adapter (NAA) output. This output supports true gapless playback of PCM, DSD/DoP, and native DSD.
Using a DAC that supports high sample rates is always helpful. I have a couple friends who love their 44.1 kHz NOS ANK DACs and their systems do sound good but after spending $6000 building their ANK DACs they are a little more than hesitant in letting me compare 44.1 kHz on their DAC (using JRiver) to the same music file upsampled DSD256 on a HoloAudio May KTE (using HQPlayer).