I think it would be a huge mistake for Bryston to try and enter this market unless they can partner with an already established company specialized in producing similar products, but then what would be the point of such a partnership? The portable world is two steps removed from Bryston's core lineup. Branching out into speakers makes sense. Branching out into a turntable is feasible since they do have phono products already and they can at least put their design chops into the power supply. But a DAP? Nothing Bryston makes really integrates with that except maybe the dacs. Bryston doesn't make small products; they have a very set range of chassis sizes and metal. Investing in something beyond that is non-trivial. Programming a dap is non-trivial. On top of that you'll also have to deal with computer interfacing and the ridiculous customer support that requires. Bryston does not make anything battery powered, nor anything that operates at that lower headphone power.
I don't think there's even a viable target market, and the overlap is much smaller than you think it is. A portable player is aimed primarily at the portables/headphone world. Bryston has only a single headphone oriented product, and it is massive and frankly quite expensive compared to what the average headphone consumer goes for. That's not to say that they couldn't design a dap if they really put their minds to it, but it would take a disproportionate amount of resources and time to create and with a very slim guarantee of even generating sales when you consider how many competing entities are out there. It's impossible to compete against the cheap Chinese daps coming out now, especially if you're still manufacturing in Canada, so that leaves the high... where your sales are even smaller. So now they'd have to push to an even higher degree of performance, sink even more resources into a product twice removed from their wheelhouse, etc.
No. Just no.
Diversifying is one thing, but this is the sort of dead end that can seriously hurt or kill a company. As I said earlier, the only way this could possibly work is if they partnered with an existing dap maker, but then what would Bryston possibly contribute to that partnership to make it worthwhile?