I'm going to offer Joe Kiani some business advice. (Like he needs it, LOL).
At the outset, merge Def Tech assets into Polk. No one cares about Def Tech, and anyone that does care would be just as happy with a Polk loudspeaker. Boston Acoustics is a dead brand. May it RIP.
Classe? Do they have a dealer network that is profitable? Is their market penetration favorable for expansion? Can they compete with Samsung (Mark Levinson) or McIntosh? Answering those questions should determine the fate of that brand.
Next, for the core. Merge Denon into Marantz. You don't need two brands selling essentially the same product to the same customers, for the same price. And, at least in the US (and probably any place except Japan), the Marantz name is more known and respected.
Second, if you must keep the Denon name, it should be only for small market analog oriented specialty product--I mean the cartridges, which probably still sell decently for a decent price. With the analog resurgence, it might be time to bring back some of the higher-end and better performing Denon cartridges, like the 103D, and the 3x series, and so on. But that's about it. Unless you want to market a higher-end record player under the Denon name, sold through Marantz dealers. If you do that, it should be something in keeping with Denon's historical legacy. A first class DD with historical Denon features--is the tooling for that still available? Whatever, definitely not a Malaysian sourced Technics SL-1200 knock off.
Third, embrace Marantz design heritage in your two-channel products. The current thing is cosmetically underwhelming and, frankly, not too appealing. It looks like every other black box out there. There is no aesthetic relationship to historical product. Nostalgia for the '70s runs high in this stuff. And, at the higher-end, where profit maximizes, consumers can buy much more visually and tactile-oriented product--product that demonstrates not only each company's heritage, but offers pride in ownership; gear that that looks like you want to place it on your equipment rack. Below are some examples so you can compare. Choose which designs are the most appealing, and then go from there...
View attachment 187454View attachment 187455
View attachment 187456View attachment 187457