I own a Marsh A400 and really value it in my system. It is very revealing of that which is in front of it. The charachter of the amp is very neutral with a huge and deep soundstage and exceptionally solid base. I have never been able to get this amp to strain even in my large room. It likes balanced tube preamps like the BAT's and cable choice is extremely important. I use the balanced inputs. I have had great luck with Harmonic Technology, Synergistic Research, and Sonoran interconnects in combination with Monster Sigma II speaker cable. The only fault I have found is an occasional glare in the upper midrange....but my room tends to slightly emphasize this frequency range. All in all, the Marsh is a bargain for the price and the amp I prefer to listen to after trying amps of all different stripes and topologies. I still keep a tube amp around for chamber music and baroque listening however. I have not heard the Mc Cormack so I cannot compare. Rest assured that if you go with the Marsh, and if you are patient and willing to change and tweek your system, you will be rewarded with transparent sound.