NuPro can not play bit-perfect

[Goran]

Hi everyone!

As a proud owner of NuPro A-200, I set out to determine if my system is playing bit perfect.

I am running Plex server on my Windows 7 laptop and stream through wifi to Chromecast Audio connected via mini Toslink to the Nubert NuPro A-200 studio monitors. Control is via Plex for Android app. I convert dts file to flac and the speakers won't play it.

Then, I tried the same with Foobar + ASIO via USB to speakers, and I was surprised: If I choose 'ASIO: ASIO4ALL V2' output, the speakers won't play. Only if I choose 'DS:Speakers (USB Audio DAC)' only then the speakers will play. Obviously, Windows DS is messing with my music files!

I suspect that USB port of NuPro accepts only 16 bit, 48 kHz signal, and that my music must be converted from 16/44.1 to 16/48 in the Windows background, so the NuPro can play the music.

Both Optical and Coaxial Toslink accept up to 24/96 files, but I suspect that 44.1 or 88.2 kHz sample rate is being converted to 48 and 96 kHz.

Now, as audio objectivist, I am strongly disappointed from technical side.
As a music lover, I can found no audible problems when I play my favorite and well-known music (all my music is 16/44.1 flac). Also, reviews for NuPro in the press are usually rave. But now my suspicion that something wrong is happening which spoils the sound never settles.

Can anybody shine the light on this issue?

With best regards,
Goran