How many speakers were you driving? Does the 8000 say it can handle 4ohms? Offhand, I'd be surprised if your 110w HK (who as everyone knows rates its power very conservatively) was underpowered for the M80s but I'd have to agree with above, it sounds like your amp is trying to protect itself -- maybe just from bad music.
Actually, I have to admit I never heard of audioslave so I went and downloaded a couple of samples -- pretty cool! Anyway, from the samples I heard, it doesn't sound like its the kind of music that has a lot of spikes or peaks (i.e. high energy transients). Does the track you were listening to have a lot of sudden bursts of energy (quick transitions from soft to loud sounds)?
