i really should've run line-in when I had one, but I didn't. but here is doug's opinion, if it matters...
"Hello !
I feel the analog noise is too audible to do much to it, especially via the TRS jacks. I feel an analog PCB rebuild is in order, perhaps let a analog PCB grounding engineer take a crack at it (not a crack pipe as these guys seem to have done !). The 3.5MM jack sounds best, hence I did do a bit to it. Mine has a full analog path upgrade but the MOD I offer is only an input overload MOD, it drops the fixed gain by 12dB, this makes it easy to use for music recording with the supplied T-Mic or DPA 4061s. Mine has the T-MOD type upgrade.
peace...Doug"