If you already have two amps you should get an electronic crossover. Different selectable gain isn't enough for bi-amplification and even perfectly matched components can go out of tonal balance turning sound onto the mess. I know that Bryston specifically asks when buying two identical amps if they must be matched and they do match for vertical bi-amp.
You can get Marchand electronic crossover SS or tube wichever you can afford and it won't break your bank or drive to the hardship of selling two amps and get one bigger. Extra interconnects also shouldn't bother you too much since in crossover domain thay mean almost nothing if quality is OK and connection is tight.
You can get Marchand electronic crossover SS or tube wichever you can afford and it won't break your bank or drive to the hardship of selling two amps and get one bigger. Extra interconnects also shouldn't bother you too much since in crossover domain thay mean almost nothing if quality is OK and connection is tight.