As Gene said, "Be careful comparing manufacturer spec sheets" on pre out specs
A couple of points to consider:
- XLR output is often higher, e.g. 2X, but may not make any difference in terms of the overall gain. For example, Bryston, Marantz and many other power amps would want you to flip a selector switch such that if you select balanced, the sensitivity would be halved. You can download a Bryston manual (such as one for the 3B/4B SST) and you will know what I am talking about.
- The specified output is often not the maximum, and based on past bench measurements they could hit over 4 V unbalanced without clipping, that would be over 8 V balanced, comparable to what Anthem specified for the AVM60
The AVM has much better noise specs than your AVR though the effects will likely be not audible. The newer Marantz AVR such as the SR7012/13 or even the SR6013/14 do have the same DAC chip as the AVM, and probably better preamp/vol control chip, now that they have been upgraded to individual chips instead of Anthem's LSI (large scale integrated). Those things are again, while differing in specs, but for practical music/movies it will be difficult to tell if one is better than the other unless you can't see which one is playing. Between the AVM60 and a comparable Marantz AV7705, I would just choose based on the feature set and price.
If you stick with what you have now and wait for the launch of the 2020 8K ready models, the price of the 2018/19 should drop significantly by then.