active crossover freqncy for Totem Mani2

It's not clear if the reason you want to use an external crossover is for the purpose of biamping. If it's not, I can't imagine you could improve on the performance over Totem's internal crossover.

If you want to bi amp speakers you need 2 stereo amps (or 4 mono amps, or one 4 channel amp). I suggest you do some research on bi amping - there are plenty of threads in the archives on this.

Passive bi amping simply connects one amp channel to the woofer posts, another to the tweeter posts. The internal crossover handles the filtering. There are 2 ways to do this - 1) Vertical bi amp places 2 identical amps on each speaker - the preamp signal is split to each channel, and one channel powers the tweeter, the other the woofer. 2) Horizontal bi amping can use non-identical amps but they need to have a volume pot so you can ensure volume is balanced. In this configuration, one amp (the highest power amp) powers the woofer, the other powers the tweeter.

Be SURE that you remove the jumpers that connect the hi/lo binding posts.

If you want more advice - it would help if you post more info about the amps you're using and exactly what you are striving for . . .

given you have 2 identical amps - I suggest you go vertical biamp. Given your preamp doesn't have dual pre-outs - all you need is a y adapter - I have my home theater front mains set up this way - I run one interconnect from my preamp for each channel - and have an audioquest y adapter ( 1 F to 2 M connectors) that splits the signal and feeds each channel on the amp. Then simply run your speaker wires from each channel to the top and bottom binding posts on the Mani.

The only way you can use your F-25 is to remove the internal x-overs in the Manis and re-wiring the binding posts to connect directly to the drivers. You do not want to mess with that and I can't imagine you will like the result after you destroy the Mani's.

you really, really need to search the archives on biamping. There is one thread on this topic that has some excellent discussion and contribution from Steve McCormack. Find it, read it.

Also, I did biamp my Mani's. The result was at best a marginal improvement. I corresponded with Totem and they indicate you're much better off using a single higher power amp than biamping - so with the Manis the bang for the buck in adding a second amp is ver marginal. Not so with other speakers, but true for Manis. That said, since you have the second amp already - get some Y adapters (they are cheap) and try it. Just do it and you will have your questions answered.

that's the one! I recall others that are useful and worth taking in as well since they all have testimonials, but it's best when there is authoritative contribution like Steve McC provided.