The person I had corresponded with before has left the company, but my renewed request has reportedly been sent "to the product team for review". In the meantime, see
http://taperssection.com/index.php?topic=192871.msg2322775#msg2322775 , which is very interesting.
I just did a bit of testing with the recorder set for automatic level control, which is something I would otherwise never have thought of doing. I fed signals into its digital input, and if I moved the record level controls, a sign came up on the screen saying "ALC" and the rec level controls had no effect whatsoever (which goes along with what I expected based on DATBRAD's message). I could turn them all the way up or all the way down; they were clearly out of the circuit (or the logic flow).
However, I didn't see or hear any actual ALC action from the recorder. I sent a set of overload-y signals in--repeatedly blowing into a mike that was connected to another recorder, whose digital output I fed into the Marantz--but there was no audible reduction in gain, and the meters registered similarly before, during and after the overloads.
So that's rather strange--but I think it might mean that the ALC setting, while not providing ALC, might provide 1:1 "bit bucket" capability. I can test for that, but it would take another hour's work or thereabouts, and right now I'm only awake temporarily (I hope) during a bout of insomnia, so I'll do that some other time.
--best regards