What non-Linn sub would work with all-Linn setup?

I have a REL Strata III and it is a gigantic improvement over my old Sunfire Mk II. The nice thing about REL: The sub hooks up to the amplifier rather than the preamp. I think it really helps integrate the sub with the amp, and brings the system "together" nicely.
So I'd recommend the REL subs because they seem to work with everything...

Do searches here, at AA at AR and HD. Lots of great reviews at AR etc. Great reviews from Positive Feedback etc. I bought mine a bit less than a year ago after a LONG search for a great sub. It definitely meets my criteria. Accurate, powerful, great pace, never gets in the way. Wonderful build quality as well. Looks like high-end furniture instead of a box. They're currently $1100 but they've announced a $50 price hike for sometime this month, check the website.

I would suggest the following 1) Aerial Acoustics SW-12 12" sub. For $4k to $5.5k, it's perhaps as good your going to find. It also offers infinite dial-in configurations and cabling options, xlr, rca, etc.. And the quality and craftsmanship is second to none. The SW-12 has received nothing but rave reviews by all professionals who have reviewed it.

2) If you're on a budget and a 'musical' sub is top priority, then I would suggest Bag End's Infrasub 18" subwoofer new about $1600 or used about $950. I have demo'ed it in my home and it is highly rated (by others) to be extremely musical. I could not believe that any 18" sub could be so tight.

3) I opted for Triad's Platinum subwoofer for $2k retail and I paid $1400 new. It's just a small step down from the Bag End sonically but offered me more configurations and options including auto-on/off. I have not been disappointed by the Triad's performance.

-John

I have a 15x15 room and am not interested in shaking the house; just supplementing the Tukans to get a better low frequency/midrange sound that is mor emusical than thudding/overwhelming. I'm concerned the Rel Stratus III and the ACI Titan II LE and the Vandy 2wq are too powerful for my humble Majik/Tukan set-up; what do you think? Should I be aiming smaller?

I don't think the Titan II LE will be "too much". It is extremely accurate, musical and subtle when required. The only way it would be too much would be if you adjusted the level to high. Otherwise you can expect a great match. This sub is known for musicality, never heard anyone say it was overpowering. Worked great with both my Concertos and now Sapphire III LEs.