Want sub to use with Magnepan 2.7' Mesa Baron Amp?

I have Magnepan's 2.7's and Mesa Baron Amp, what sub should I use new and used? I do not want an exaggerated base. I want to expierence more of what base the Mesa delivers and fill in where the Magnepan's leave off.
Help please!
Vandersteen 2wq.
The vandersteen will work if the input impedence of the Mesa is 100k or lower. I have used these with stats and maggies and it is great, but the amp has to be able to use it.
To match up with planars you need a great sub. The Titan II LE is a great sub. Took me a year of auditioning and researching subs to decide on the LE. Man am I glad I did. The only sub I heard that I'd rather own is the Aerial, and it is about 4 times the price! If you want the opinions of others read the reviews in Positive Feedback, BFS, Soundstage etc or do searches at AA and AR. Great people to deal with too.
REL subwoofers are specifically designed to fill in the bottom below your main speakers, without using a cross-over that would change your main speakers. Easy to integrate. They connect to your amp along with your speakers, so they get the same signal.
I second the Rel Recommendation. I have a Baron Amp and use a Rel storm and am VERY happy with it.
I can definitely give you me thumbs up for the REL subs. Fantastic with Maggies, I used the REL Strata with the Maggie 2.7's, match made in heaven.
I change my vote! Just say no to "Dick" Vandersteen products. God forbid if you have a question and need factory support, they make good products but buy the REL or anything but stuff made by him.
Thank you everyone for your input, remarks and time. I am looking forward to trying your choices.
Thank you everyone for taking the time out to pass on your advice.