A subwoofer is a great idea in my humble opinion. I found that using a good subwoofer to augment the bottom end of a Martin Logan set-up was well worth doing. Over the 14 years that I had my Quest Z's, I bought, (and sold), a bunch of different subs. Some I found worked better and blended seamlessly, while others were pieces of crap and only "muttled up" the sound. The good ones were: Velodyne, but NOT the big ones. 15" and 18" drivers can be too slow and plodding, did not mate well with a "fast" panel speaker such as M.L., so stay away from the BIG Velodynes, like the FSR18, F18, ULD15, ULD18. I've owned them all. Go for the smaller driver Velodynes if you must. IMHO. Von Schweikert used to make a pair of subs, each containing two rear firing active 10" drivers in a sealed cabinet. Called the Towers of Power. Those were killer with my M.L.'s., (they were a completely black fabric covered pair of subs and looked like Vandersteens). Had them for many years and loved them. I ultimately ended up with a JM Lab/Focal Sub Utopia which is an awesome match, and just seemed to fill in that bottom octave without imposing itself. Very smooth and natural, and it's a beautiful looking, furniture grade cabinet with a 1000watt amp built in. It's built like a battleship. I still have it today and use it in conjunction with my MBL 101e Mk2's. Other subs I've bought over the years, but didn't like with my M.L.'s, (and ended up selling off pretty quick)- ANYTHING Sunfire. Had 3 different sizes of those little Bob Carver designed "true subwoofers"...basically a little nuclear bomb in a box. I found them to be sloppy and loose, and boomy. Not worth the trouble. To hard to integrate, crappy sounding. They're really just good for lots of noise, but suck for music.
I've also had one of those BagEnd "infrasub" 18's. The thing was GIANT, produced big boomy sound, and was slow as MUD. It's much better if used in a home theater system with the LFE output. Great for explosions, car crashes, Sci-fi space battle scenes, and loud sound effects. But NOT with music. NOT with M.L.'s
I would stay away from those if I were you. Now Martin Logan makes some great subs,(the Depth, the Decent, the Abyss i think they are called??), and while I have never owned a M.L. sub, a friend of mine did and loaned it to me, it was clear that it was intended for use with "fast" speakers, and really worked wonders with my Quest Z's.
So there you go Lostbears, from my firsthand experience I would tell you to go for it! Buy a sub and you will not be disappointed. They add a whole new dimension to an already great speaker. Just stay away from the crappy ones I mentioned. I see M.L. subs all over this A-gon so I know you could snap one up for a pretty good deal. Better yet go for stereo subs...buy 2 M.L.'s!! That would be a beautiful thing!
