Kanto SUB6 Subwoofer

A subwoofer is a tremendous improvement to any speaker setup, whether it's used for music or movies. By relieving the other speakers of reproducing the bass frequencies, they will play with less distortion and the bass will give the sound a much larger sense of room-filling presence. A decent sub will also give you bass that you can feel. However, I'm not convinced that one of these smaller subs will do any of that. I recently upgraded from a cheap 10" subwoofer, to a DIY build based on the 12" Dayton RSS315HF driver and the difference is huge for music, movies, and video games. With that said, the addition of the older sub to my bookshelf speakers with 6.5" woofers was also a very big deal.

The StudioMonitor 350 are bookshelf speakers with 1" tweeter, 5.25" woofer and 8" passive radiator. That passive radiator really works quite well, giving the speakers great bass extension, but my only gripe is that it's a bit weak. That's why I was considering adding subwoofer. I get what you're saying though, 6" is just way too small to be a particularly good addition to what I already have. With that in mind, how big is too big? I'm mostly looking for a subwoofer for music listening, not home theater. I've seen BIC and Klipsh subs on sale every now and then, but wasn't convinced something meant for home theater would be ideal for just music.

A sub that's physically smaller than the speaker it's complementing makes no sense. Your StudioMonitor 350s already have better bass extension than this "subwoofer." I can't imagine pairing this with anything larger than 4" satellites, and even for that purpose it costs too much for what it is. If you already bought a decent pair of bookshelf speakers, consider buying a proper sub that's at least 10," or preferably 12." I would recommend Parts Express. Their subwoofer kits are very nice if you're willing to spend a few hundred dollars. Otherwise, the cheap Dayton subs (~$100) are very good for the money.