First Watt vs McIntosh vs Ampzilla


I'm searching for a power amplifier to pair with a McIntosh c712 preamp and Zu Omen Def speakers. 
I want it to be melodic and clear (not mellow and round) and with a good soundstage, capable of filling my big living room (12m x 6m) with powerful party levels sound - not necessarily ear splitting levels.  
Nearby I can purchase a First Watt M2, a McIntosh MC7150 or an Ampzilla 2000 (stereo) for a good price. 
I cant audition them at home with my system, so besides my personal opinion on the sound at the different shops, what do you have to say regarding these three models? Any of them is better than the others? Better sound? Better reliability? 
Any opinions?

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The M2 has been my only amp for the past 3 years, and paired with my Spendor 1/2s and AI Modulus 3B (or Quicksilver Pre), it is an astonishingly good sounding component. It does everything well, imo, and will reflect accurately what is upstream, whether it be the source or pre, etc. It creates 28W and will rock your Zus, guaranteed. The one caveat is that Nelson Pass  specifies its noise w/o signal at 500uv, whereas the other First Watt amps are slightly quieter. The music mine makes, though, outweighs this minor fact, though...it is a  keeper. 
First watt with your speakers should pair very nicely. Class A with those speakers is the way to go. 
Biggest mistake I made was selling my GAS ampazilla amp. Tons of power, quiet never came close to pushing its limits.

I think your Zu Omen Def speaker can easily go with tubes. My tube amp Cayin CS-100A KT88 has about 70watts p/c and is very dynamic and clear with a little bit warmth. With your efficient speakers you will be able to make party. It is not necessary to have 200 or more watts. The quality is more important than the power. 
Any of the three would be nice. That said, the 3 times I've seen Sean demo Zu's it's always been with Pass gear. That would be a strong endorsement for the First Watt.