I use 3 AB400's and 3 SB-900's and I love them all. I find that the 400's kick out plenty of power for a small setup (and so do the SB's for that matter!). I went with the 400's because they are a little cheaper and the recycle time is a little quicker. I've had the AB's for over 2 years now and they've been solid, dependable workhorses.