Have your friend contact Mapletree audio an get an SCC1System Configuration Controller, I had them make me one last year it controls 2 amps and 2 sets of speakers along with 3 inputs, CD, phono preamp and streamer, you can switch from one amp to the other while both amps are on and warmed up you can even have them make the router for 3 amps.
My cost was $450.00 delivered and it only took 2 weeks to get. Just call them and talk to Al Freundorfer a.freundorfer@gmail.com