I've run SBD mic in without any problems!!
I haven't tried a soundboard in, so I can't comment on how well it would work. I'd almost definitely use an attenuator between the board and the DR2d. That way I could control the input level, and do so in practice due to the attenuator -- give a range of 65-100, not just set it and hope.
I have for the past year and never had any problems except once when the SBD had a bad channel
and that was fixed by tossing that channel when post processing and duplicating the other channel
I just must have the benefit of having FOH guys who work with me beforehand... so there is no illusion of control for me
I don't want to get in the middle of someone else's pissing match, so please keep me out of it.
I'm just saying what I would do, and what I think is good practice.
To run 4 channels into this recorder, 2 from an external mic preamp, and 2 from a soundboard, you will be running 2 sets of line level inputs into a recorder that only has 1 line level input and one mic level input.
The DR2d's mic level input can only take a -16 dbV input. The nominal line level for consumer gear is -10 dbV and the nominal line level out for professional gear is +4 dbu. A soundboard is likely in the latter category, so a nominal output level of +4 dbu.
I think the person asking the original question should know this, thus my point of posting. If running without an attenuator is working for you, that's great. I'm just saying I wouldn't do it, and frankly, I wouldn't recommend it. But people can run their gear however they want, I just think itis useful to know some of the issues to consider.