Yes, I have heard it. It is very good at its price point. For comparison, most cheaper Cambridge players have a forward sonic balance with fairly flat frequency curve, meaning that bass and treble are not attenuated in favor of mid range tones, as some other manufacturers of budget players prefer to do (NAD comes to mind here). The other Cambridges tend to put their empahsis on resolution and timing over soundstage width and depth - so you get musical details and tunefulness, but not necessarily the best "hiFi" effects. The DacMagic is at the very musical end of these characters, having essentially the DACs and upsampling electronics from the CA 740C, which is one model and several hundred bucks down from the 840C.
For comparison with the player you are familiar with, I find the Rotel sound to be fairly accurate and flat in frequency resoponse, but somewhat sterile or dry (lifeless is probably too strong a term) overall in comparison to say, the Cambridge 640C, the Dac Magic or 740C.
The 840C on the other hand to me sounds warmer and more liquid through the mid range than its littler siblings. It keeps the tunefullness and resolution, but wraps it in a tropical breeze, and does a better job of building a believable soundstage. Soundstage size is still not top o0f class for the Cambridge compared to other players in its price range, but the other things it does well more than compensate in my mind.
The reason for the leap in capability for the 840 over its sibilings probably results from the fact that it uses a completely different set of DACs and I believe different algorithms for upsampling among other upgrades. In any case, your amp has balanced inputs, and if you fit the 840C with good balnaced ICs and a capable and compatible power cord like the Analysis Plus Power Oval 2 or Shunyata Diamondback Platinum or better, you can maximize the positive traits (including expanded soundstage) for both CD playback and use of the 840 as a stand alone DAC serving other sources. I think you would enjoy it.
