How to integrate a sub with 2-channel mains?

I've done a ton of searching and haven't been able to come up with an answer to this... Hopefully some of you can help!

I currently am running a DIY BP1503 for my home theater/television, and it is everything I want for that. Howerver, I want to get a second sub for 2-channel music; probably a UFW-10, something much "faster".

What would be the best way to integrate this with my mains? I've seen many people post that they did this, but as near as I can tell, they are not using their processor to xover the mains and sub... How do they hook these up and cross them over?

Thanks in advance!
I use a paradigm x-30 crossover with my 2 channel setup and sub. You can pick one up for around 100.00 used.
Most subs have built-in crossovers in the plate amp. most will have low pass (I think that's right) for the sub. some like the adire shiva se will have a plate amp (hypex hs200 I believe) with a high pass for the mains, if you want to roll them off and prevent bass from going to the mains. most don't have a high pass or simply don't want to use one and run the mains full range. it just depends on which is the worse of two evils. I prefer to run mine full range and just use the sub for the bottom octave.

most will hook up the sub using secondary pre-outs from their audiophile 2CH preamp or integrated amp and a long pair of interconnects. some don't have secondary pre-outs and instead use high level (speaker level) inputs to the sub, like the vandersteen sub does.

I should be receiving my ACI Force sub in the next few days. I have Magnepan 1.6QR's that I'll be blending this sub with. According to my research, some things to consider are: (a) Speed and size of the sub's woofer. Big boomy subs might be great for home theaters but too sloooooow for music, (b) Flexibilty of crossover frequency and phase controls. Most subs, in my case anyway, don't allow a low enough crossover to integrate with my Maggies that are -3db @40hz. Typically, most subs have fixed phase of either 0 or 180 degrees, (c) Hook-up flexibility in regards to line level inputs and outputs.

Anyway, my research led me to manufacturers like REL, Velodyne, Vandersteen and finally ACI.

Good luck,

Thanks for all the replies!

Abrahavt - how would I use the ICBM? just use it for the sub?

Radiob - do you use the x-30 for the sub only, and run the mains full range? I'd like to avoid any unnecessary processing on the mains if possible.

Aroc - your technique is exactly what I was thinking. Is it better to run the mains full range and augment the lower registers with the sub, or to cross both over?

As far as outputs; I am getting an AVM30, and I don't think it has secondary outputs; so I'd be stuck with speaker level inputs. How is this done? Attach another 2 wires to one of the speakers binding posts, and run it to the sub?

Beatlebum - I knew the bp1503 would be too "boomy" when i finished designing it; the alignment has a mid-q, around .7-.8 IIRC; I think it's better now to use it for HT and get a smaller for music.

I was looking specifically at the ufw-10. Here are the specs:

Other Features: One-band parametric EQ (freq, bandwidth, and level), continously (infinitely) variable phase, gain, and crossover adjustments (40Hz - 150Hz), crossover disable option, LFE summed R/L RCA input, balanced mono XLR input, auto-on / standby mode.

Thanks for all the responses! Sorry to keep asking newbie questions!
I run the Mains full range. Here is a trick,Reverse your + and - on your mains, put in stereophile test cd 2 play the bass wobble tone and adjust the phase of the sub with a rat shack db meter until the db is lowest, then correct your main + and - and your sub will be perfectly phased. This is far mor acurate than by ear.