a dipole sub with a high quality crossover that won't hurt the Maggies is not possible at your price point, you would need to go way higher, especially for the crossover...the REL T/Zero works great with smaller Maggies but does not filter out bass to the main speakers...
Subwoofer suggestions for budget system?
My current setup is a pair of Magnepan 1.6 speakers, a pair of Schiit Vidars, Schiit Sol turntable w/Goldring E3 cartridge (I have a VAS-rebuilt Denon DL-103 with Ebony shell and microridge stylus when I can get someone to come set it up for me), Mani 2 phono stage, Asgard 3 headphone amp acting as preamp, Schiit SYS as source selector, Modi 3+ connected to Volumio for streaming digital and an Orchard Audio RCA-to-XLR converter to drive the Vidars in monoblock mode.
I'd like to add a subwoofer to the mix that can keep bass out of the Maggies. I'd, of course, prefer a dipole sub to go with the dipole speakers, but not terribly picky ATM. My budget is around $200 to $300 for now. I have been very tempted to build a pair of my own subs, but that's not in my budget right now.
Suggestions?