One of the ideas in last post was to re-bias Acurus A250 amplifier which currently drives supertweeters. Here's a discussion on exactly this sort of thing with a virtually identical Acurus A200, where it is claimed by several posters that increased bias removes the steely highs of this amplifier:
Increasing bias to 6-7mA (measured across 0.5 ohm emitter resistors) is said to improve highs immensely.
It's not entirely clear to me if the R11 potentiometer is the bias adjustment; that's the only potentiometer I see on the schematic. Is there no offset adjustment then?