Hello,
Still don't know what went wrong. To close to the stage? Using preamp without bass roll off?
--- Sorry for my english ----
That's a shame
It sounds like an over-driven analog stage to me. Either your mic was overloading (unlikely with 138 dB max input) or the mic-preamp was getting a too-hot (loud) signal (possible?). I think it's most likely you were feeding the mic input to the R-09 too loud a signal so that the analog stage is being over-driven over-driven prior to the D/A.
You note > Edirol R-09 (24/48, input lev - 8, AGC off,
EXt mic - stereo, Low cut - on, Mic gain - low)
The solution would be to use the line-in not the mic-in.
EDIT: I see you used line-in (are you absolutely sure?), in that case the high/low gain doesn't make any difference to the input that only applies to the mic-in. If it is the case you used line-in you were feeding it a too loud signal (lower the gain on the pre-amp).
OR
Were the batteries in the preamp going flat?
digifish