However, I realized the next few hours that there are also a few problems (mainly with the HDMI Audio).
The Radeon cards have a very good energy management that reduces dynamic overclocking power consumption (at low load). But this can cause the while watching TV (via DVB-card) or when watching videos on DirectShow audio output dropouts or crackles gets are so often they overlap partly the sound almost completely. I quickly realized what it would probably lie and the DPC Latency Checker confirmed my guess.
The Power Management the card or more specifically actually the drivers cause up to 4000μs latencies (normal are latencies below 500μs in a system with reasonable drivers). Bring to the card (eg by a game in windowed mode) to 100% of their power to run these lag no longer exists. Confirmed, and a solution (for me unfortunately too late) you can find in the Forum of AMD (keyword "audio / sound dropouts").
The solution, however, leads to the map in the desktop operating no longer underclocks and thus consumes more electricity. I'm waiting now first as AMD eliminated this problem and will long live on my 7900GTX.
