And that selling point is why people so often push for modular surround processor designs for companies like Outlaw. The reality, though, is that nobody seems to have ever successfully made it work. Plenty have tried, including some big names (Onkyo) and some smaller names (NAD). None have been able to translate the promise of easy modular upgrades into actual practice, at least not fast enough or consistently enough to make much of an impression.

The closest I think anyone has come to this are Anthem and Lexicon. Anthem took the AVM20 platform and built off of it for over a decade (and counting), with a mix of new products (AVM30, AVM40, AVM50, Statement D1, Statement D2, AVM50v2, Statement D2v2) and upgrades to those products (adding ARC to existing units, etc.). None of it was truly modular, and most required either buying a new unit or handing the existing unit off to a dealer or the factory for the upgrades. None of it was cheap, either, and at this point there's probably precious little left from the AVM20 (aside from the chassis dimensions and basic layout of the faceplate) in the current hardware. Lexicon's MC12 has been similar, with the basic platform tweaked, upgraded, and expanded over the course of many years. Neither was ever really marketed as "modular", though.