Jack
It's just getting better and better, huh?
All the above input is valid.
My exp is such that no one piece is more key than the source... but one wouldn't put a $5K CDP on a $500 INT amp, now would they? some sense of balance generally pushes things towards higher levels. The culmination of things allows the signal to be realized as being improved upon.
some will stick to spending more on speakers first and moving towards the front end (source), other's will think exactly opposite of that and drop tons on the front end.
The relationship between speakers and amp is pretty important, very, actually. once that is in place, either first or later on, or even last for that matter, the source is going to be where many go to get system wide gains.
simply throwing money on a source, without bringing up to par other pieces of your gear, you're spinning your wheels.
try out some new footers on that Cambridge... or play with it's power cord next. If you've not done that you aren't done addressing the source completely.
You seem to have liked what the new Cambridge did for your rig already. good. Perhaps now address some other area of your gear next. Maybe cables, or conditioning, even isolation.
My ideas are based on simply what I've exp'd. I've heard great sources, with great preamps and amps, on modest speakers, and it sounded beter by far than mid fi electronics on great ($$$$$) speakers.
Seemingly minor changes too, can be remarkably interesting and most positive... and fun.
Enjoy.