Optimal sample rate and bit depths for Devialet Expert

[Confused]

I have tried upsampling to PCM, upsampling to DSD and also various filter options as available with HQPlayer. The first point I would make is that the difference between sending bit perfect and upsampling is far smaller than the difference you might experience between different quality sources and indeed between the various input options.

So I would look at the quality of source first, mindful that all other things being equal, the AES/EBU input is preferred and is generally reckoned to be better than the Devialet's USB input. That said, the sound quality that can be achieved using Devialet AIR is now so good that you would need a very decent source to better it.

I have tried DSD upsampling with both Roon and HQplayer, whist it nominally sounded quite pleasant in some respects, I did notice a definite reduction with bass definition, this was not for me.

Currently I upsample PCM using HQPlayer, which allows me to 'fine tune' very slightly using the various filter options. This is playing with sound quality very much on the limit of what can be observed I think, but does make a minor difference. In short, I would say use a decent source via AES/EBU, the rest is 'fine tuning'