Subwoofer recommendations for Spicas TC-60's?

Just to go in another direction, I would first dig into the Spicas and upgrade crossover components and internal wiring.

Did this with a pair of TC 50s and they were incredible. Tightened and deepened the bass considerably. Opened up the mids and the highs became much airier. Vocals came close to my Rogers LS3/5As.

By invite took them back to the shop from whence they came and trashed the stock pair on the floor.

I'm using TC-60's with 2 -Dali Suite 1.2 subs. They are acoustic suspension subs and they are not boomy at all. I had a filter built by Tom Tutay for my TC50's that plug into the input of my amp (Modified ST 70 by Tom Tutay) that rolls the TC 60's off on the bottom end and then the subwoofer takes over. It is a smooth transition. Remind you my filters are for the TC50's not the 60's. But they work just fine for my 13' x 14' room.
The TC-60's are ported and actually go much lower than the TC50's but they are ported in the rear. Rear ported speakers are a little harder to mate with subwoofers 's. My room is small and really the TC60's alone put out pretty good bass response. I am also Tri-wiring them.

I have two wires running from the negative tap of my amp and one of each wire (top woofer & tweeter negative) is connected to the negative posts on the Spica. No jumper on the negative side. I have a single jumper on the Positive side (joining the woofer and tweeter) and one wire running from the amp positive (8ohm tap) to the positive (jumpered connection) on the TC60's. I can only tell you it really did something to the soundstaging and depth of soundstage of my Spicas. I tried it on some other speakers I had come through and it didn't work as well. It's a mystery to me!I'm using some inexpensive 12 Ga Vampire Hook-up Wire CCC (hard to find now) and it really sounds great in the tri-wire setup. It runs around $2.00 to $4.00 a foot if you find some. Michael Percy was the last to have any we could find. You can get it in 18 gauge from their site but we were only interested in the 12ga.

Experiment a little by switching your TC60 around with the ports on the inside vs the ports on the outside. That should for some reason give you a little more bass.
I would also reccomend you get a pair of subs rather than a single sub. Things are more coherent.

You want a sub that has a very good crossover with both a high pass filter and low pass filter. Correct me if I'm wrong but the high pass will control or rolloff the TC60's and is supposed to blend the TC60's and the Subs better.

Not all subs do this as well as it should. Thus the reason I chose to do it the way I'm doing it. I would rather have a separate amp and stereo crossover and two subwoofers like the kinergetics setup.

I would look at Parts Express also for their subwoofer offerings. Several manufactures use their parts for their subs. I honestly can't say that the big bucks that the REL or Velodynes and others offer will give you that big of bang for the BIG Bucks! My room doesn't require me to spend that much and I'm happy with my Dali Suites righ now.

Hsu subs are wonderful for what you are doing. Whatever you do make sure the subwoofer is fast and can keep up with the little TC60 woofer. So far I don't have a problem blending the Dali Suite 1.2 subs in my little room. Play with the phasing too. It makes a difference.
If you are doing Home Theater that changes the game somewhat. I wouldn't use my Spicas in my Home Theater setup. They are too good for that and I only use them in my 2 channel rig. Check out the Spica Enthusiast on google or type www.spicaspeakers.com . You may find some more information there. Goodluck.

most likely candidate would be Kinergetics subs they were made just for the spicas. I would still look for a Rel sub there a bargain on the Gon for what you get and they mate well with almost all speakers..