Let's get something straight - if you have a subwoofer - you NEED an active crossover to limit the frequencies sent to the main speakers, and the subwoofer too,
if you want ideal performance. You don't run the main speakers full range when you have subwoofers except in what I consider to be jack-leg set ups.
You have two options of feasibility here. One option costs more, but does a better job.
1. Buy a stereo receiver that has pre-amp outs and direct amp-in connections on the back where bridge pins normally route the signal back to the internal amp. Harman Kardon has a decent unit
factory refurbished for about $200 with this feature, model HK3485. Buy a new Behringer CX2310 for $80, a few XLR to RCA, and RCA to XLR adapters, and route the receiver pre-outs to this, then route the subwoofer and mains signals from this xover - back to the appropriate signal input jacks on the receiver and subwoofer.
2. Buy a good quality, but low priced(preferably factory refurbished for best value) surround receiver that has variable built-in active crossover. The Onkyo SR-505 is the best deal around. Factory refurbished for $130, in
black or
silver; that's about half price from what it used to cost new. It has the benefit of unusually good quality for the price - like all of those SR-*05 models seem to have had. It even has a nice solid metal front plate instead of the cheezy plastic found on almost anything else in that price range.
Number 1 is the best option. The external crossover has steeper crossover slopes on the mains and it has a higher level of variability of crossover points. You are more likely to get better integration. But number 2 is a fair option with more limited xover functions. Also option 1 has about 50% higher power output and is 4 ohms stable. The ability to insert processors between the amp and pre-amp also allows for even more sophisticated processing. For example, if you opted for a Behringer DCX2496 xover over the CX2310, you would have an incredible range of processing abilities at your disposal. If you planned to go with really nice speakers and subwoofer or multiple subwoofers, this DCX2496 is incredibly useful and will allow you to adjust the sound signature to your preference(s). It is far more than just a xover - and even it's xover functions are beyond what normal xovers can accomplish.
-Chris