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

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.