I have an Arcam Alpha 8SE CD/HDCD player that I use daily, and I should take it down to the store & listen, but I'm afraid to truck it around town. I have KEF Reference 103/4 loudspeakers. I will be replacing an Adcom GFA-555 and Adcom GTP-500II pre-amp if I pull the trigger. Any thoughts???In your current system you have a high rez source and high rez speakers. Your Adcom electronics in between are the weak link. They can't approach what that 840A can do. If the 840A with a good source was "stunning," then you know how good it can sound, and your Adcom stack could never rise to that level of resolution, refinement, or performance regardless of the source component.
You need to try your Arcam into the Cambridge or just go ahead and buy the 840A on faith. If you "are afraid to truck it around town," make an appointment with the audio store to bring it in and audition the 840C. Don't hesitate because the buzz on these Cambridge Azur components is deservedly good and I doubt an 840A would hang around long at $800.
Your Arcam should handily beat the old Denon, and may be as good as the Cambridge 640C that was feeding the 840A on your first demo. If it's not, you can get a new 640C v2 from Audio Advisor for $399.
I say get the Cambridge 840A NOW. If it doesn't impress you as much at home as it did at the shop, start saving for a better-sounding player to go with it. You'll ultimately be glad you did.