One feature you might want to look for is a steep rolloff slope for the variable-frequency lowpass filter. You want to rapidly roll off the top end of any subs that are closer to you than the main speakers are, so that they don’t pass upper bass/lower midrange energy loud enough to give away their presence. (The ear tends to localize by arrival time, which is why this matters for subs closer than the main speakers.) If that’s not possible, then use a lower low-pass frequency setting for subs that are closer to you than the main speakers, and a higher low-pass frequency setting for subs that are equal distance or farther away than the main speakers.
In case you decide to "roll your own", here is the amplifier I use, which has a 24 dB per octave lowpass filter:
https://www.parts-express.com/dayton-audio-sa1000-subwoofer-amplifier-rack-mountable--300-811
Parts Express offers several passive subwoofer kits (you’d have to paint or othewise finish the enclosures after assembly).
So does SpeakerHardware.com. I designed three high-output 12" subwoofers which are offered as kits by Leland Crooks of Speaker Hardware. (I don’t get any royalties or other kick-backs from the kit sales, just so you know.) Four of these plus the Dayton Audio amp would strain your $2k budget, but I mention them just in case.
Duke
Swarm guy
In case you decide to "roll your own", here is the amplifier I use, which has a 24 dB per octave lowpass filter:
https://www.parts-express.com/dayton-audio-sa1000-subwoofer-amplifier-rack-mountable--300-811
Parts Express offers several passive subwoofer kits (you’d have to paint or othewise finish the enclosures after assembly).
So does SpeakerHardware.com. I designed three high-output 12" subwoofers which are offered as kits by Leland Crooks of Speaker Hardware. (I don’t get any royalties or other kick-backs from the kit sales, just so you know.) Four of these plus the Dayton Audio amp would strain your $2k budget, but I mention them just in case.
Duke
Swarm guy