If the amps do not have the same output gain then you would have whatever boost the difference in gain is for the higher gain amps frequency push - otherwise you would need an external crossover to match the gains if that is what you want.Depending on the built in crossover some rooms benefit from non-matching amps to boost the bass frequencies a bit.
Bi-amping for me?
My new (used) speakers have this funny bridge between the terminals which I correctly assumed are for bi-amping. The dealer I boughtthe speakers from thought that I would get some added benefit from bi-amping. I'm going to ask a stupid question and please don't jump down my throat: do both amps in this scenario have to have the same output? The speakers run at 4 Ohms so can I assume that tubes would not suffice in either scenario. The speakers sound good with my present amp (threshold S300). Are there any articles you could recommend? Also would like some guidance with x-over units...From what little I understand, this is a controversial subject (i.e. the proposed benefits of bi-amping). Thanks.