I have an AVM-20 (v2.10), and have tried both digital-in and analog-in from my CD player. In the analog configuration, I set it up to use Analog-Direct mode, NOT the Analog-DSP mode, because I don't want ANY A-to-D & D-to-A conversion going on.
So, you could setup two inputs in your AVM, say the CD input for Analog-in and AUX for SP/DIF Digital-in, then connect your player to both inputs. This will allow direct, A-B comparison with the same equipment, and will 'probably' convince you that the AVM's DAC's are NOT optimized for 2-channel audio, which were my findings. You have invested in a player with a tube DAC optimized for one purpose, so I really doubt you will disagree once you try this. I was very amazed at the big advantage that my Arcam player's DAC's had over the AVM's.
But here's another kicker -
I just added a Pass X2.5 2-chnl pre to my setup, so I could avoid using the AVM at all for stereo. I suspected the AVM was not passing the signal purely to my Pass amps, even over balanced XLR connections. Well, the difference in dynamics, detail and stage-width that this traditional pre has over the AVM is just staggering.
I have never been a "2-channel VERSUS Home Theater" type, fully convinced that you could successfully use a quality HT pre/pro as a standard pre, but I now know better. If you take your 2-channel sound seriously, I would recommend that you investigate adding a pre to your setup.
Many pre's, like the Pass X-series, have a Unity Gain input (or at least a Tape Monitor loop circuit) to allow the integration of the HT processor back into the 2-channel pre for multi-channel use. I have not completed a major rearrangement of my system yet, but this is the way I intend to configure my setup.
These are just my observations (YMMV, IMHO, of course), but when I told my dealer what I found, he confirmed that this is nothing new. This is not a cut on the Anthem processor, just a confirmation that there is always a compromise in 2-channel performance when using M-channel processors. He also said that most people that take both HT and 2-chnl seriously he deals with will either separate their music and theater systems entirely or do something like I have to get the best out of one room and speaker/amp investment.
I hope that helps.