I think it's due to the greater challenge / complexity involved, that most "audiophile" companies aren't up to the task of. Remember, esteemed as they are, the audiophile companies don't actually do much innovative or challenging design work. They buy their CD transports from someone else. They buy their power amp transformers from someone else. They buy someone else's vacuum tube, or they buy one of TI's DAC or opamp chips just like anyone else. They do the integration work, then dump it into some nice big, spacious chassis that's assumed to be fed an unlimited amount of power from the wall socket. They basically don't have nearly as many design constraints.
Imagine in contrast the portable DAP. Actual R&D is required. You can't use off-the-shelf parts and hope to be cost competitive. You have to devise your own compact power system. You have to devise a storage system. You have to come up with your own DAC. Who's going to do that? Can Wadia design its own custom DAC integrated circuit rather than relying on a burr brown product? Where is Linn with its lithium battery cell? When will we see Krell design a storage medium with an innovative new form factor? Probably never, which is when we'll portable audio devices from such players.
Well, I take that back. Once the rest of the industry has developed DACs and opamps and power cells that make "audiophile" portable players possible, *then* we will see these companies jumping into the ballgame using off-the-shelf parts combined into the package that you are looking for. Until then, you either have to deal with what's on the market, or you have to hope that one of the upscale divisions of the larger consumer manufacturers takes on the task. For example, Sony Qualia could do it.
