Hi Aercool,
Fancy meeting you here!
I've been wanting a First Watt for a while. I'd love one of those new SIT stereo amps, but not about to spend the money.
Did the M2 take care of that problem Lucinda Williams track? If so, I'd be quicker to blame your Zu's than the amp. I'm powering single driver Omegas at 93db sensitivity and at 5wpc or so with the Pope 6V6 power tubes. If I recall, you've been running 6550's which should give you twice the power. I didn't get the bass clipping on that track at all.
But you've got a potential solution there with the First Watt. It's a push pull, so I've been hesitant about it. I'd love to hear more about how it compares, in the various qualities we like to talk about, with the Inspire.