I tried to play a 24 bit 44 kHz flac file on my e71, but all I could hear was white noise. It works OK for 16 bit flac files.
I used Oggplay v1.72. Newest beta did not work at all, it did not even play 16 bit files, but stopped at the very beginning after like 100 ms.
I checked it with CorePlay and it works OK, so it is clearly not a hardware problem.