ODAC Rev B trouble


I am operating Volumio on a CuBox i4 Pro with an ODAC as Sound Device. Everything is working wonderful.
A few days ago, I ordered the new ODAC Rev B and that DAC is giving me a poor performance.
The output level is only one third of the old ODAC. The noisefloor therefore is hearable. Audio mixer is disabled.
The producer JDS Labs says in his Tech Specs that the audio level should be a little higher than the old ODAC was.
Also the new ODAC Rev B needs to be driven by a USB HUB, the old one could be connected directly to the CuBox.
Under Windows everything looks fine, the new ODAC performs as good as the new one.

Has anyone an idea?


So, today I´ve done some measurements with an Oscilloscope.
I did the measurements with a FLAC File from AUDIO Soundcheck with 1000Hz sinus@0dB both channels. The output was terminated with 47kOhm.

Volumio 1.5:
Output ODAC Rev A: 2.8 V peak
Output ODAC Rev B: 0,2 V peak

Windows 7, all Mixers at 100%:
Output ODAC Rev A: 2.0 V peak
Output ODAC Rev B: 2.0 V peak

I can´t believe, that this is a problem with the DAC. I think that there is a parameter in Volumio preventing the signal going to 100% or the DAC is not recognized correctly on the USB bus.