I actually did not think I would hear the difference or need the C-10X for my M-10X when I was using the C-900U. I thought "how much better can a preamp make" when the C-900U is so good.
Turns out I was completely wrong. From the moment I first hooked it up, the soundstage is clearly larger. Image has more depths. Bass is stronger and tighter and high end is more detail. I’ve been listening every night for 2-3 hours and enjoyed it. I honestly think the C-10X is a proper and great upgrade over the C-900U if you’re running the M-10X. It really matches with the M-10X well. I can confidently say that I heard better improvements in sound on upgrading the C-10X from the C-900U than having one M-10X in stereo vs. 2 M-10X in mono.
The one very minor dislike I have with the C-10X is the volume knob resistance. It’s less resistance to turn the knob. I felt the C-900U has the perfect resistance and this new knob is too loose. However, most of the time, I use the remote so doesn’t really matter. Just that I've lost that great Luxman volume knob feel. :D
