Franche, I have an Outlaw 7500 and a pair of ML reQuests. I previously had a top of the line Yamaha receiver--which, like you with your Sony, I used as a pre-amp--and a Classe CAV-75 amp (6x75w) which I used to passively bi-amp my reQuests. While I can't provide any insight on the Cinema Grand or the MCA50, I can attest that the Martin Logans sound great with the Outlaw 7500 and that it was a significant step-up from my previous Classe amp. The 7500 is rock solid and I'm very happy with its sound and build quality.

btw, I replaced the Yamaha receiver with the Outlaw 990 and have enjoyed that upgrade as well.

Rob