I have an AVM 20 and it is fine. Good solid AtoD and DtoA converters - you will probably get a little jitter on digital inputs though (just because of the interface) - but the analog direct is clean and the volume control is superb (resistor network on a crystal chip) - I found that a power conditioner helped slightly on digital and I prefer a Benchmark DAC1 for music (edges out the Dto A in the AVM 20 but you got to listen very carefully to notice it). The main advantage of this DSP is its incredible list of features and flexibility - however it is outdated now given the newer HDMI and BD formats.
AVM 20 or AVM 30 vs Mid-Fi Yamaha Receiver
I am currently running the pre/pro portion of my Yamaha RX-V659 Receiver with a Sunfire Cinema Grand II amp (5 x 225W) with 3 Von Schweikert LCR-15s across the front and VS T-150s as the rears. I am debating upgrading to an AVM 20 or 30 and wanted opinions as to whether or not it would be worth it based on the other equipment I currently have in the system.