I can say that I own the HD-P2 also for fieldrecording, and use AKG c1000s and Shure 109A, with both of them, I have the preamp maxed out completely - and that do make some hiss noise - or it makes too much!

How is yours there?
Yes, might be the wrong mics for the job, but it's brand new to me, and got it with the mics, so surely up for suggestions!