Question on using bi-amp...

If I understand your message correctly, you are not trying to biamp in the normal sense but instead, you are trying to connect both amps to the same set of speaker terminals such that you can switch amp at will (base on the kind of music you want to play I presume). I strongly suggest against it because if you forget to turn off one amp before turning the other one on, you will fire both amps and your speakers. Even the amp is turned off, it will definitly have ill effect to the other amp and to the sound in general.

Don't do it.

A safe way to switch amps is to use a switcher box. There are many different designs available but unfortunately I do not have enough experiences in them to make recommendations. Maybe other members can help.