I had the same experience running the C165 through the C275. Very one-dimensional sounding. I am currently using a Wyred 4 Sound STP-SE with the C275, and it is a VERY good match. Very clear, nice, clean bass...it’s a winner!
The W4S is a very unique design. It acts primarily as a passive preamp, but has 6 dB of gain that it can tap into. For me, it solved the problem of having so much gain that the volume control range was limited to between about 8 and 9:00. I got real tired of preamps with an unusable remote volume.