Times are a-changing... So: time for the geniuses at Bryston to develop a new BP-XO-DA.
My perfect DAC would have the connectivity of a BDA3, plus at least 2 analog inputs. Digital volume control (skip the headphone part, that should be a separate "power"amp), stereo analog outputs, and a user programmable (software like Arta) cross over filter which sends out a two or three way analog output signal to go into separate poweramps like the 24B3 for active loudspeakers. A Lyngdorf-like RoomPerfect option would also be awesome, since soundwaves may come from loudspeakers, but the room that is listened in determines how it actually sounds.
Apart from the RoomPerfect this is all equipment Bryston alrealy builds, so it would basically be a matter of combining.
