Hmm, some pretty blue-sky thinking in this thread! Some good, some I like less.
On the question of the remote control, I can see some value in being able to alter the volume from a nearby sofa, but other than that I don't like the idea at all: remotes are flimsy, irritating, they get lost and I've got too many of them. Given that most users are going to be tethered to their amp by a length of cable anyway, I don't see this as something that would make me buy one headphone amp above another; in fact, it's a slight dissuading factor.
DSP has a longstanding bad reputation with the hi-fi (let alone audiophile) buyers, and while I rather like the idea of having options to play with I also know that it's going to detract from the listening experience because I'll always be wondering whether tweaking a setting would improve the sound. The thing about the current crossfeed circuit that I like is that Headroom sticks its colours to the mast and says: "this is the best we can do, this is what we're hard-wiring into our amps". The danger with DSP is that it ends up looking as though you're saying: "Hell, this is all too complicated ... YOU figure it out."
If there are going to be DSP elements, I'd like them treated rather like they are on the Line 6 guitar products: pseudo-analogue, with notched presets and dials. Many people are already feeding their headphone amps from a PC; they don't need another PC on their amp, and the watchword should be only including what is essential.
That said: having all the switches on the front panel sounds good, I'd like a wireless connection option, Dolby Headphone yes please, and multi-channel inputs sounds interesting. A screen (with a "screen off" option please) would be fine, although really I go back to the point that if the amp needs any sort of screen then it probably has too many options.
Perhaps most intriguing to me is the idea of some form of music storage and playback, but that would need to go in another box and I'm not sure how economically viable such a player would be. I suppose that my ideal would be a hard disc recorder capable of accepting analogue and digital signals as well as capable of being filled directly from a PC. (Once you've got the ADC in there, you'd effectively have created the natural descendent of the Walkman Professional, and it could be used for a number of recording purposes. You could also have an "analogue passthrough" so that if you were recording, say, a concert, you could listen directly on headphones from the amp without decoding the signal twice.) I don't know why Headroom would want to get into that business (it sounds like expensive R&D to me) but having all this stuff in another standalone box might mean that Headroom could offer the bells & whistles on that box and leave the amp itself comparatively minimal.
So, I suppose that I basically incline to a Pre-amp/Power-amp combo, with whatever fancy stuff you want to put in on the Pre-amp and a Power-amp that feels exactly like an evolution of the existing line.
By the way: I'm 39 and spend a lot on technology, so it's not that I'm taking a Luddite approach to the digital side at all. It's just that by the age of 39 I've seen and owned so many flashy, poorly-engineered and quickly-superceded pieces of kit with a digital element that I've come to believe that there are some areas, such as music reproduction, where a fairly minimal and distributed system is far preferable.