Whether one sounds better to the other or not I can't say, because it depends on so many factors. In theory if the distortions are below the threshold of audibility, frequency responses are less than +/- 0.5 dB full range, there will most likely be no audible difference, all else being equal. That's for preamp/dacs and power amps, for DSP, there could be little to very audible difference between units that have different DSP chips and implementation, but then it is still tough to say if others reported brand A better than B, will you or won't you hear similar kind of difference. Like food, people have different taste/preference.
Now the specifics, the Yamaha RX-A3080, as you probably know, have the ES9026Pro for the main 7 channels, and the ES9007 (same as the 9006 the best I can tell, as the ES9006 seems just a different number for Yamaha, may be a few others, cannot find the datasheet anywhere for the 9007.
The AVM90 has the ES9038Pro, and as far as I know, you probably cannot find another (may be 1 or 2 that I missed, not aware of, perhaps Arcam's top model?) AVP that uses such an expensive real reference class DAC chip.
The AVM70 uses the ES9038Q2M, that is virtually as good as the ES9038Pro. Both chips have specs well above that of the 3080's ES9026Pro, but the difference may not be audible.
Back on the subjective side, you can read a lot on forums and it is common to find that owners tend to say nice things about their expensive gear vs the cheaper ones. So yes, you will read a lot of Anthem users reporting much better sound quality from the AVM90 over the AVM70, many would even claim "night and day", huge improvements going from the 70 to the 90.
I spent some time listening to the 90 in the dealer's demo room and I could not support such claims at all. Yes the AVM90 sounded great playing the dealer's demo movie tracks, but to me, there is no night and day difference even compared to my AVR-X4400H based on auditory memory. There is no way, and I am certain about it that someone without real golden years can identify the 90 from the 70 if in a blind comparison listening test. You should be able ask for a AB demo comparison between the two as most dealers likely have both setup.
If I heard any easy to tell difference offered by the AVM90 I would have bought it, but I settled for the 70 and am very happy about it. I like AVPs/AVRs that uses the better DAC ICs, regardless whether I could hear a better difference or not. Anthem has that edge, in terms of using better DAC, and likely the important volume control ICs, and that makes me feel good about theirs.