Biamp question

I thought I could. I’m just not sure about the logistics exactly. 

The gain on Parasound is adjustable so I believe I should be able to match the gain by adjusting on the Parasound to match the Rogue. I’m pretty green here so not sure that makes sense or not. 

Honestly I am not sure how to use the built in crossovers of the speakers. Seems the connections would be different. Please excuse my ignorance on this topic. 

Do you need to pay attention to the crossover points or are they going to be pretty standard?

I guess I won’t know that until I try it. On the crossover question, I want to get a crossover that already matches the crossover points of the speakers. Is that pretty accurate?

Now I’m thinking/wondering if you need to have 2 amps that are exactly the same to use internal crossover wiring method. 

Thank you all. I have not tried the st 100 by itself yet. Are you saying that not only is it stout enough to drive the bass on the legacy’s but that you also prefer the sound of st 100 over the a21+?

Oldhvymec thanks for your advice and input. I will give that a try. Thanks to everyone else who commented for your input as well. This has all been quite illuminating. 

I do have one last question. I am assuming that both amps inputs go to the same preamps outputs. Is that a correct assumption?

At my current abilities I would be very hesitant to use an active crossover since I would actually have to get inside the speakers and disconnect built in passive crossovers in them. The nice 7 year Legacy warranty goes out the window and if I make a really bad mistake potentially a pair of $9000 speakers go south. I guess when I started this I was looking for an easy way to use these 2 amplifiers that would make a sonic difference without adding active crossovers and opening up my speakers. 

I have also read that when you go with passive biamping that since the crossovers being used are at the speaker level that the preamp still gives the speakers the full range of high and low frequencies. I can’t seem to wrap my head around that since one amp is going to hf and the other amp is going to lf. Seems like crossover of the speakers would prevent any upper frequencies from going to the lf and lower  frequencies from going to hf. Apparently the built in crossovers of the speakers cannot prevent that from happening in the same way active crossovers can? If that’s true is it because preamp sends everything and speaker crossovers can’t filter properly? And if that’s the case it would seem I would lose the implied benefit of the tube amp handling hf and ss handling lf. And I’m pretty sure I am the most confused person in the room right now. 

Thank you all! I believe I can manage the active crossover (possibly) but my chief concern is disabling the crossover in my speakers.