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.



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...

I disagree w Millercarbon.

That said, how about an SVS Micro 3000... that comes w all sorts of adjustability, crossover tweaks, equalization to a certain extent even.  



$200-$300 will not buy you a very good sounding subwoofer. Keep your eyes open for a used Martin Logan Dynamo 1000W, (hopefully around $400 used). They are excellent for music, very un-colored and "quick" sounding. Also, a used REL T-7 series for around $500. 

Keeping the bass out of the Maggies requires a subwoofer with a low-level high-pass filter that can be set to 60Hz. In turn, that requires line level cables to the sub and back to your power amp, adding complexity and expense to your system, as well as limiting subwoofer placement. The SVS 3000 Micro is the least expensive subwoofer that I am aware of that would complement your 1.6s and has adequate bass management.