Having auditioned the same Acurus at hom with Aerial 6's, I found a similar lack of weight. I traded up to the larger 3 channel B&K, which was better, but ultimately to a 9b. Very, very satisfied; you are not buying 5 3b's. I have reconfigured into a larger system using Aerial 8's, and added two 7bs'. The 8's definetely benefited from the extra power, and I was pleased with the intergration of the three amps. Unless your speakers really need the extra juice, however, I don't think you can go wrong with a 9B.
9B-ST for Home Theater Amp
I am using an Acurus 125x5 for the home theater surround setup, but I think my speakers need something with more bass control. The "slam" that I like is just not there in the mid-bass and lower frequencies. Can I get that out of a Bryston 9B-ST? I have the 4B-ST for my separate audio system, and the thing rocks. I'm worried that with a 9B I'm basically just buying 5 3Bs. Anyone have any other recommendations aside from Bryston? I thought about waiting around for the new 6B-ST and combining it with a 4B-ST, but then of course I'd have to get a new amp for my audio system. Ahh, decisions, decisions. Input would be appreciated.