More channels don't do anything significant for music. In fact, movies could bake in virtual surround for headphones on a stereo channel. You could have "surround" with 2 speakers as well, read sound bars, however the sweet spot is too tiny for practical purposes most of the time.

While 16-bits is absolutely enough for normal listening conditions with high end gear, for archival purposes 24-bit would be wiser, as this would enable you to drive a grand concert stage at maximum quality just in case. The added hi-fi khz are a total waste of space however.