To speak to your specific question, my best friend and I both recently finished setting up similar bi-amped systems and we both needed a lot of DSP to make it work (active crossovers, delay, compression drivers with response that needed EQing, etc.). He went the hardware route, and I went the JRiver route, so I can tell you first hand some of the ups and downs.
He started out with a Behringer DEQ, but that wasn't really adequate for his DSP needs, and he switched over to its cousin the DCX2496 which has six output channels, more flexibility, and more DSP options. He's quite happy with the DSP his DCX gets him, but it is limited (the DCX only supports a fixed amount of processing/number of filters, and a fixed number of channels in and out). If he wanted to expand his set up (i.e. surround sound) or if he wanted to do much additional EQ he'd be bumping against the limits of the DCX. Additionally depending on how you use the DCX, it may involve a A to D conversion followed by an additional D to A conversion, which (while probably inaudible given the high quality conversions the DCX does) is another two conversion steps in the signal path if you care about that kind of thing. Each of those boxes retails in the high two hundred dollar range.
By contrast JRiver supports an arbitrary amount of DSP with many more options, and is only channel limited by the number of output channels on your soundcard/HDMI output. JRiver provides customization that's pretty hard to find in hardware, and it also retails for significantly less than either of the boxes. There's a bit of a learning curve with using JRiver, but that's true of the boxes too.
To summarize, for the price of JRiver and an 8-channel Asus soundcard I have DSP capability that exceeds what my friend can manage with the DCX, a comparable DAC, two fewer conversion steps in my signal path, easy integration with computer-based content (youtube, netflix, etc.), enough output channels for a 5.1 surround system (even after losing two to bi-amping) and it cost me about half what he paid.
The DEQ (as opposed to the DCX) has some non-DSP functionality, like RTA capability, but there's free RTA software out there if you need it. You'll also need a calibrated Mic though (I'm not sure if the DEQ shipped with one or not)
If there's any specific DSP functionality you're curious about with the DEQ, the DCX, or JRiver I've got access to all three and can find out if I don't know.
- Only applies to audio played through MC itself (so it can't be used on other applications, like games)
Also @Glynor- I use loopback to output through JRiver with Games all the time. As I understand it the surround support isn't there, but I use JRiver to output all audio on my PC regardless of source.