Originally Posted by Red MC
I was going to suggest the same thing, with the caveat that you have to be a little bit techy to configure it. But I doubt you'll find something cheaper.
Another option is a PA crossover:
In the audiophile world, external analog crossovers are kind of rare these days. The only current offering I know of that's reasonably priced is the Marchand Electronics XM46SB for $295. But it's also an ugly box with inputs & outputs on opposites sides, that you'd want to hide away. Marchand makes units in nicer boxes that look more presentable on a rack, but they are $800-1000.
Two discontinued options are the Bryston 10B-Sub and Outlaw ICBM. Every once in a while, I see one on the used market. The Bryston commands high prices, but the Outlaw might be reasonable if you can find one.
If it were me, I'd probably get rid of the Denon and Adcom and replace them with a good quality used AVR. Old 5.1 models that predated HDMI are cheap as chips. They will have a DAC as well, so you can run digital out from your sound card. Sound quality with old AVRs is a bit of a crap shoot, so you'd have to do your research. The reason why I like this option is that it simplifies the signal path.
Finally, I guess I should have asked this from the beginning, but what's your goal? Running stand mounted speakers full range and using subwoofer(s) to fill in the bottom end is a valid option. Are you trying to offload bass from the MLs so that you can play the system louder? Or just trying to improve the blend between the speakers and sub? Personally, I've found that optimizing the placement of the speakers and subs can make a huge difference in how seamlessly they blend, more than any electronics. I don't know how much flexibility you have in placement and how much effort you've put into it, but definitely make sure you've exhausted all your options there.
Yes, I want to improve balance, and to be able to play it louder, both
Basically I want to be able play around with crossover points and slopes if possible, a para EQ would be cool, etc. Techie doesn't bother me, I'm a programmer by trade. I just want to tool around with the setup. I do a have a sub, nothing special just a JBL 10" with 250W rms. Actually blends real nice, but I plan to upgrade it at some point.
My reticence about getting such a receiver as you mention is that, really, this AVC-3030 is a monster AFA consumer-grade AV components go, at least afa the power section on the three front channels. It's Made in Japan, 33lbs, Class A, with a Torroidal Transformer, 2*15,000ufd caps, and 120 watt Sanken large cased transistors. 110W * 3 into 8 Ohms at full range with .03 THD. Preamp has a dead silent noise floor. No joke, it's a NICE unit.
However, using it as the preamp only, and the Adcom for power ... still sounds noticeably better than using the Denon alone.
Thus, I feel like I'd have to drop a significant amount of coin even for an old receiver to match this sound quality. To get a high pass filter, primarily? I'm thinking probably not for this setup
I'm totally not averse using the Toslink from the PC and using a digital processor as long as it sounds good and doesn't add noise or otherwise degrade things. I'd love the DSP linked above, that's PERFECT for me ... I just don't like the 'form factor' you might say.
TBH I'm considering just upgrading to floorstanders so I don't have to worry about it. The Monitor Audio Silver 300's are seriously calling me ATM