Keep the amp for now &
try open baffle, spatial or pure audio
or listen to the recently reviewed
raven audio speakers
Then back into the right electronics for your choice. That said Im not sure why you think you need extra efficiency w All that Pass power
I haven’t heard the combo but vandersteen Treo CT or Quattro CT
Should be very compatible, granted not all watts equal, sort of speak, but 75 watt AudIo Research amps are highly compatible and those are not efficient speakers
try open baffle, spatial or pure audio
or listen to the recently reviewed
raven audio speakers
Then back into the right electronics for your choice. That said Im not sure why you think you need extra efficiency w All that Pass power
I haven’t heard the combo but vandersteen Treo CT or Quattro CT
Should be very compatible, granted not all watts equal, sort of speak, but 75 watt AudIo Research amps are highly compatible and those are not efficient speakers