"Serge Auckland" wrote

Only issue I can think of is that the QUAD power
amps need only 500mV for full power.

The Quad 405-2 signal input level:0.5V rms +/-
0.5 db for 100 watts into 8 ohms. Amp loads
input by 20K ohms in parallel with 220 pF.

Signal input overload: instantaneous recovery
up to +20dB overload.

Stability: Unconditionally stable with any load
and any signal... according to the brochure.