[sebhoff]

I've just received my new TubeMagic D2, and I'm experiencing odd distortions - the D2 seems to overmodulate (correct word? - sorry, am not a native speaker of English...) in some places. It doesn't happen throughout - but again and again when the sound level is high enough. This happens regardless of whether the input mode is optical or USB. I have an ESI Dr. DAC prime to compare it with and its output is fine with the same music (and the same settings).
 
I can get rid of the distortion if I reduce the output volume of Audirvana by about 2dB - but the Audirvana manual recommends that volume should be set at 100% to avoid a reduction of the digital audio signal precision.
 
Any idea what may be the cause of this? Is this a faulty D2 or am I likely to be doing something wrong?
 
I'm using: 
- Hardware: MacBook (Retina display)
- Software: Audirvana
- USB or optical connection to the TubeMagic D2
- Little Dot MK9 headphones amp
- high-quality (but not high-end) cinch cable
- Beyerdynamic DT990
 
Any ideas/suggestions?
 
Sebastian