One of these:

http://emotiva.com/umc1.shtm

One of these:

http://emotiva.com/xpa5.shtm

Or better yet, one of both of these:

http://emotiva.com/xpa2.shtm
http://emotiva.com/xpa3.shtm

(Lots of Maggie owner's swear by these amps, see Emotiva's forum)