Glad to hear you're enjoying your M80s.
One caveat I'll mention on complex components with "modular upgrade capacity": while in theory it would seem to be ideal, several engineers I've spoken to, including a former Axiom engineer, reject modular AV receiver designs because of potential long-term relibility problems.
The multi-pin modules typically require many tiny plug-in pins that over time may or could become intermittent.
Onkyo tried a modular receiver some years ago and abandoned that type of design. When Axiom considered developing an AV receiver, I spoke with engineer Tom Cumberland about a modular approach. He rejected it immediately because of the aforementioned problems.
Perhaps NAD has overcome these engineering objections with their modular approach.
Axiom Resident Expert