If you really want to know or confirm, I suggest you contact Roland directly. They picked up the phone within 30 secs when I called on Friday. Or submit an email request.
Digital Recorders and Mixers: 323-890-3741
http://backstage.rolandus.com/email_support/
sorry to bump an old thread, but i have been very curious about the "unity gain" on my r-09 lately...
i realize that we have had lots of differences of opinions here and so i decided to call the support number above to see if 2 years later, someone there now has an answer.
sad to report that the guy i spoke with does not have an answer and was actually very condescending on the phone when i was speaking with him. Saying things like "have you even used this thing"
His solution was to use the preamp meter and match it to the r-09 meter and when they were the same then I was not adding gain
... not quite sure that is a real solution, but whatever...
fwiw, i asked if there was a set number or range where the line in signal was attenuated or if it was all gain. He stated it was all gain. I asked what about the 0 which was a "mute" function, and that was when i was told "its real easy, just match the meters".
kinda disappointed in the level of service, but maybe he was having a bad day or possibly really didnt know his shit.