how to hook up subwoofer?


Hi guys, this may be a atupid question here. There's an auction here in town today where all the stuff of a higher end audio store that closed is on sale.

I thought about getting a subwoofer if the price is right but wasn't sure how to hook it up on my 2-channel system since there's no dedicated output.

I've got a Musical Fidelity A308cr preamp and a pair of Electrocompaniet AW220 amps.

Any input would be greatly appreciated.

Thanks
krauti
Thanks guys for your help. The subs they had were mainly B&W ASW608's and most of them sold for about 350 to a little over 400. Considering that the auction house charges another 10% on top of it I figured it's not a bad deal but not the best either.

Settled for a demo Rotel RCD 1072 CD player for about 300 bucks since I don't have any half way decent player yet and will address the subwoofer issue later.

Might just breplace those B&W 703's with some PMC OB1's that I heard a while ago and liked a lot better.

Ok, Happy Turkey day
Post removed 
"You can also connect the sub to the systems Tape monitor outs....." Always a bad idea.

Kal
You can also connect the sub to the systems Tape monitor outs but variable Pre-out might be better as you have to adjust the volume if you use the tape outs and usually can adjust the volume less often when using the preamp variable outs
Not your preamp inputs but, perhaps, your preamp's outputs! OTOH, there is no generic answer since we do not know what connections the unidentified sub has.

Kal