Bit of a late reply, but I used to use a JB3 with SP battery box and SP mics.
Then I got an Edirol R09, and when I first used it I carried on using the SP battery box (with bass roll-off to 0)
I found that I lost almost all of the bass from the recording (bass cut off) The SP mics were the same as before.
I stopped using the battery box and used the mics direct, with plug-in-power and it improved the sound no end - much more low end than before.
No help at all with this recording, but it might help a bit in the future.
Best of luck