Marsh or McCormack

I have own the McCormack DNA 225 amp, it is an excellent ss design from a well established company(currently owned by Conrad and Johnson). Build quality is excellent with quality parts. I haven't heard the Marsh amps but they have received excellent reviews in The Absolute Sound. If you have the chance listen to both in your system. I don't think you could go wrong with either one but I bought the McCormack based on sound, company reputation, dealer network and support. Good luck.

Listen to both if possible.
I would take the TAS Marsh review with a grain of salt (tho they also reviewed and were impressed by the McC) as they have also raved about products in the past designed by Marsh that I thought were disappointing, like the Monster power conditioner. Marsh used to work for TAS.
I'm not really suggesting an consistent editorial bias, just be aware that rave reviews are not a good enough reason to buy an amp.

I'll continue to promote the virtues of the McCormack DNA-225. Oodles of CLEAN, QUICK power. Can't speak to the Marsh, but if you've narrowed it down to these two amps I know you like the 225.

I don't have a comparison between those two, but I was in a shop that carried McCormack and Linn, I compared the 225 with the Linn AV-5125, it's a 5 channel amp. They were very close in sonic signature on the system I played them on. I had a couple tracks I was playing, my wife liked both on the Linn and I liked one on the Linn and one on the 225. All that tells you nothing as a comparison between the two in question...but I thought I would share my experience.

I can't give much info outside of this as I wasn't familiar with the system they were used with.

B&W will give you a good sound, depending on placement, and room conditions. But no equipment can improve the source material.

The gear, and especially tweaks, are of little consquence until that is maximized. The gear is way less significant, and tweaks are still of little consquence.

Specs for a good amp:
Distortion: <1%
Damping: >20
Watts: what the speakers need
Verify inversion non-inversion in your system

Then pick the gear that looks good in your system, and color coordinate adequate cables from the many there are to choose from.

The rest is primarily phycho-acoustic game playing and hair splitting.