Guys, I just got an open box Cambridge 351r for my modest HT with mission M3 speakers. I did a lot of research and many raved about the good sound on this unit. I am finding it very dark, and with the meaty, rich sound it has - too warm and muffled with speech especially. I am sure the Mission M3s are not helping here as they are warm (though i thought the pairing would work as i have a Cambridge stereo amp that sounds great with them). So, I am after experiences, thoughts, ideas on whether this characteristic can be corrected with brighter speakers and whether you have any issues with the dark nature i am hearing - not enough air or sparkle. Also, I would be very grateful if anyone with experience of both can comment on the differences in sound quality between the C351r and Marantz NR1504, which i can change this for at the store but cannot audition it there. I am wary of swapping it for the Marantz only to find its a step down in sound quality in other departments. To note: I am limited to slimline amps due to space restraints. Any help much appreciated.