this is really not currently feasible in RAM.
But that's irrelevant from Snd's point of view -- it normally only
keeps 8K samples (or is it bytes?) in RAM for each open channel
or mix -- are you thinking of some other editor perhaps? One
of my standard "regression tests" operates on a 6 hour stereo
44 khz sound.
Anyway, I looked at the spreadsheet-for-sound business, and I
think I can make it work in Snd without great pain -- you could
use it that way now, but not easily. I'll poke at it further.