As
@m. zillch mentioned, for D+M models, PD and even D mode behavior could vary among models. In general though, in those modes if analog inputs are used the device will keep the signal in the analog path.
In terms of bass management, then as
@lovinthehd alluded to, some models would still let you have some basic capabilities such as crossovers, speakers small/large (older models, newer ones use different terminology now..).
I suspect models at the 4000 series and up, at least the ones that have the two channel stereo menu, would let you have crossovers, speakers small, but the lower models is somewhat confusing as a) they don't offer the two channel stereo menu, so you get only the general menu to select small, large XO etc., without one specifically for two channel. In those models, I have only tested the AVR-X1800H, and I had used REW to verify the results, so I know for this near entry level model, even though I can still set XO, small, large, it actually has no effect, so the FR plotted with REW would show flat FR regardless of crossover settings. I didn't like that because it was obviously misleading but I understand why D+M would not likely care because I assume they know most who use these lower models would not care that much about such level of details anyway.
Note: I think the higher models could still offer the basic management settings because there are ways to do it, without including an analog filtering circuit, though iirc, the super high end ones such as the AVR-5805 (confirmed in Gene's review), and so likely the AVR-A1H, AV10 might (not confirm anywhere but in one of the response I received from Marantz support a few years ago, the rep claim that's the case with the AV7705) also have such analog filter circuitry (confusing too, not sure exactly how it's done, as he called it "tone control" for such purposes.
