Interesting, thanks guys. Just to be clear I'm not looking to upgrade the AVR any time soon, but I had figured I might need to look into at least a dedicated ADC if I was serious about getting high quality digital files from analog sources. It sounds like you are both suggesting the onboard Yamaha ADC will be as good as a reasonably priced aftermarket external ADC?
I had thought a few hundred bucks (eg Focusrite Scarlett) would get me a decent step up, but I'm happy to stick with what I have if a meaningful upgrade would be pushing into 4 figures.
Cheers,
W