... I have setup MC to use asio4all together with a USB dac (HRT Music streamer). When i play "normal" audio (example uncompressed Flacs) all things go well but when I play some highres files MC crashes. ...
What is the exact device model? I searched for "HRT Music Streamer" and it seems to support only up to 16-bit / 48 KHz (assuming the third party review sites provided correct information). It seems to be a discontinued model and the manufacturer's site does not provide any technical details or a downloadable manual. If you have some other model it may support higher sample rates and bit depths.
ASIO, Kernel Streaming (and WASAPI Exclusive on Vista and newer) are strict modes. The HW device driver must support the played format natively.
Interestingly no matter what setting i set "Direct sound" / Asio / Kernel streaming, MC crashes when playing high res files.
This is odd. Assuming you have a correctly working device driver installed, Direct Sound should work in any case because the Windows mixer on XP resamples and sets the output bit-depth automatically if needed.
Actually, what do you mean by "high res files"? Sample Rate, bit depth, number of channels, file and compression format, ...?