Well I owned a GFA-5800 which was I think the same design but with fans for cooling.
The bass was phenominal. Bascom King did the review of that amp and loved it saying it bettered amps selling many times it's price and he especailly liked the bass calling it Krell-like. There was nothing wrong with the headroom. I wouldn't call it grainy either, misty maybe, and that was it's main failing -- the highs were not the best.
I sold it and replaced it with a Threshold S/550e because I didn't like the fans and i've missed it on my subs ever since.
The bass was phenominal. Bascom King did the review of that amp and loved it saying it bettered amps selling many times it's price and he especailly liked the bass calling it Krell-like. There was nothing wrong with the headroom. I wouldn't call it grainy either, misty maybe, and that was it's main failing -- the highs were not the best.
I sold it and replaced it with a Threshold S/550e because I didn't like the fans and i've missed it on my subs ever since.