Instead of a Y cable running to both amps you use an A/B switchbox instead. One more switch to flip. This would be to get ideal impedance match between the preamp and the amp. A switcher would not do near as much harm as an unpowered amp input load sitting on the active one. Yuck.

I don't believe an 861 will do it either.

- Fiddler (IMHO)

If you think listening to music is fun, try learning an instrument.
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