Bi-Amping Which amp for highs and which for lows?

My rule of thumb: Whichever way sounds best!

Pick the better amp of the two and biwire rather than biamp.  

If you decide to go for biamping have you confirmed that both amps have the same gain?

Unlikely they have the identical gain, so padding one down would be necessary.  You could use a high quality capacitor in the high input to roll off the bass, and use a volume control of some sort in the bass input to match the output.

What would the advantage be of adding another crossover (the capacitor) ahead of the HF input of the speaker?  

I think the OP would need some decent measurement gear to get that volume control set correctly.

I still am of the view that bi-wiring with the best amp rather than bi-amping with different amps is better approach, but I wish the OP success regardless.

Agree about bi-wiring rather than bi-amping, unless the OP is very savvy and dedicated.

What is OP?

what is the diference with bi-wiring?
i was goona use the A-B outs on me HK3800 to supply the juice to my individual drivers in the MT project

OP is "original poster", which in this case is you.

@canibefrank, probably better to use double runs of same cables, connected to same output of amp and separate terminals on speakers.
Bi-wiring uses one amp, bi-amping uses two or more amps.

wow, i did not know you could do such a thing.
is bi-wiring preferable to bi-amping in a dual driver full range enclosure? i am building the Castle MT with Alpair 7 drivers

If the speakers have separate binding posts for highs and lows, then, yes you can run two identical runs of speaker cable attached to a single output post on the amp and each binding post on the speaker. Don't use the A and B posts on the amp.

Thanks Tomcarr

I am running the highs with the A5 and the lows with the A2. Speakers are P-37 and they do sound awesome. 

That's great!
Enjoy the music!!!

OP, suggest you confirm that the two amps have identical gain.....

I checked and they both have 29db voltage gain. Why does the gain make a difference?

If the amps have different gain, you won’t be driving the HF and LF sections of your speaker equally.  If the HF amp has 2db more gain, then it’d be as though your HF drivers are 2db louder than they should be.

If you are happy , that’s all that matters and you can safely ignore this thread. :)

Amps are the same gain

On paper....  :)

Yes on their manual