Originally Posted by Kevin Haskins
That is a great solution if you want four. But most of the people building these are doing one or two and like most DIY projects cost is very critical to the overall equation.
Well, my first argument is that people should be considering more than two subs, especially when each one is cheap and in a form-factor that makes them relatively easy to hide.
I also tend to be very worst-case scenario with my numbers. The cheapest recent '2535 on eBay sold for ~$160 shipped. A miniDSP can be had for as low as, what, $120 including shipping and the plugin, assuming you don't want their box.
But second, there are plenty of outboard 2-channel amps out there (even old AVRs) that are cheap to buy (free, if they're already sitting in one's proverbial closet - the reason the 2535 sprung up in my mind is because I have one of those not currently in use) and could be easliy repurposed. A chip-amp plate solution with a bespoke milled faceplate is a stellar option for people who want to keep it all in the box, too. But as an outboard amp, I don't see much point in a bespoke solution when there are new 2-channel amps that seem adequately powerful for the task widely available for under $100, and smaller 50-100W/ch used amps from Adcom, NAD, Parasound, Rotel, etc. also being very cheap. (Or for more power, there's always the Behringer A500 for ~$250.)
Another idea would be take an old multichannel HT amp, or even an old receiver, and add a small sub per channel. All the better if you already have the thing lying around somewhere! (Even something like an old Panny XR55/XR57 should work well in this application.) More, better bass at low cost! And if old the AVR's crossover goes low enough, that would be a great way to facilitate a "ULF + BroadBand" subwoofer setup, too. Though if memory serves the Anarchy tapped horns don't go all that high.