While you do have to check the response, most pro units will work fine. (The DriveRack is actually for another purpose than crossover and is well beyond what I would suggest in this case.) The problem I have often found is not limited LF response but limited low range on the crossover setting. That is also true of many audiophile crossovers; some manufacturers (like Bryston) make a special subwoofer version. Mine comes in TRS or XLR versions and I think the model number is dbx 223xs (there are several flavors with various I/O and number of crossovers built in, and you can get it in black or silver). Check it out at Sweetwater (www.sweetwater.com);
I think it runs around $200. It is an analog unit using a standard L-R (Linkwitz-Riley) crossover design so is not as flexible as the miniDSP (which is a digital processor so you can do a lot with it). But, it is much easier to just plug in and go. If you want to explore more advanced options and build a measurement and correction system then the miniDSP is a great way to go. From there you quickly run into thousands of dollars for higher-end stand-alone units.
* Checked the specs: Bandwidth: 20 Hz to 20 kHz, +0/-0.5 dB, Frequency Response: < 3 Hz to > 90 kHz, +0/-3 dB. My system provides bass to about 10 Hz (-3 dB) in-room with a pair of F12's.
My past experience with Behringer echoes Enrico's and I would not suggest them (but I have little recent experience). The Behringer DSP-based units are used in some high-0end speakers but again is likely overkill in this application.
I use the crossover for sub and mains as the L-R design is a good way to match slopes and phase. I do not notice any loss of sound clarity/whatever to mains or sub.
If you want a better, or at least more expensive, analog crossover then Marchand would be my advice.
Letting the mains run full-range is one of the few, if not only, areas where Magnepan and I disagree. I am just one unknown guy, but OTOH I have measurements and a lot of listening made by myself and many others over several decades to back me up.
FWIWFM - Don