Sunfire amps

I'm looking for a beefy amp for hometheater and have been looking at sunfire amps for a while. Now they've come out with a new line of amps. I'm interested in 5 channels, so my choices are the original cinema grand signature 405x5, the cinema grand signature II 425x5 and now the 400~5. Other than minute changes in the wattage, does anyone know of any difference between these amps that would impact the sound. The sunfire website offers absolutely no information on this. I'm also interested in people's opinions as to the musicality of this amplifier as I'm going to stick my pioneer 47a in this setup for multichannel DVD-A and SACD.