I compared the c320bee vs. the RA01 vs. the 540a and picked the 540a. It really came down to the NAD and Cambridge units as Rotel charges $100(!) for their remote and for my office app., a remote is a neccessity. The speakers are Mission Argonauts (4ohm nom., 95dB/w/m). Here's a summary as to how they compare to each other:

NAD C320bee:
Superior bass response, very musical, neutral tone, looks only a mother could love.

CA Azur 540a:
Better low level response (i.e. more balanced at all volume levels), slightly warmer tone, very musical, far better aesthetics.

If you want more bass, the NAD is the way to go. Given enough juice, C320bee plays deeper and with more authority. I use mine in the office so low level ability took precedence and because they are out in the open for my clients to see, aesthetics played a role as well. The Azur runs cool and hasn't had any problems whatsoever driving a 4 ohm load 10 hours a day for the last 2 years, although I doubt the NAD would have encountered any difficulties either. With the Mission's sensitivity, it isn't like I'm pouring power at 'em. NAD has had some previous QC probs, as has CA. In fact, I had to send mine back to replace the volume pot barely 3 months into ownership. Since then however, it has been bulletproof. BTW, I got mine from a dealer for $250, so realize there is room to negotiate.

Both are very good units. You can't really go wrong with either.

Hope this helps.