High bias mode the amplifier was excellent for classical music but not so good for metal or hard rock, perhaps softening the transients.
If that were the case, then the amp or it’s power supply is not up to scratch for the current draw of the high Class-A bias mode, and is being starved/overloaded somewhere.
As more Class-A in my experience should if done right, only makes everything even bigger, more transparent, less hard and 3D, as well as the bass not being 2 dimensional. And the sound should sound like it’s coming from everywhere in the image but not from the speaker drivers themselves.
Cheers George

