AFAIK, the R-05 has a hidden menu that provides balance control, just like the R-09 did. Check the TS thread on accessing it's hidden Easter-egg menu. IMO doing so would only be useful if you are always using the same mics with an channel imbalance and wanted to avoid having to re-balance for that every time in post.
Even then, doing it in post would likely be more precise, unless the R-05 can adjust balance in 0.1 dB increments, which I doubt.
If I had this problem, I'd measure the exact difference in output between the two mics, then make a project template file in my DAW that has the one channel adjusted by that amount to compensate.
Roland r-05 sounds interesting. Any experience with the balance control menus? Don't want to be fumbling a lot in stealth mode.
Thanks
TS thread link -
Roland R-05 has secret easter egg menu for more settings too! http://taperssection.com/index.php?topic=136806.0R-09 provided balance control in it's secret menu. I assume R-05 does too. I don't think it is something you can or would want to try an adjust while recording. Rather, it's a measure-and-adjust-beforehand, kind of thing to generally equal out levels as a good starting point.
As stated previously, I'd only bother with that if it the mic sensitivity was significantly off-balance, but I readjust the balance-level of all my recordings by ear as need anyway even if the level difference between channels is spot on. There are other factors a balance tweak can adjust for, and in the end a correct subjective psychoacoustic balance is more important than a numeric level balance.