Im doubting bit depth is relevant.
Actually, bit depth is extremely relevant, although it might not be the only solution to the problem stated by the OP.
While the points being made in this thread about headroom and getting above the noise floor are all relevant, one of the biggest advances in recording technology in terms of ensuring success in the end is 24bit technology.
There are plenty of threads in ts.com history to explain the technical reasons for this, but in practical application what happens is that you can run your recordings with FAR more headroom in 24bit without losing any sound fidelity. In 16bit, you need to run as 'hot' as possible (having levels close to peaking without actually peaking) because that provided the best sounding recording and the best dynamic range.
99% of people using 24bit will record with LOTS of headroom...leaving their levels so they only peak somewhere between -6db and -12db...then they will bump their levels in post.
In 24bit, doing it this way virtually eliminates the chance of peaking during the show and results in little or no loss in sound quality.
I basically agree with what everyone else has said, but here's my suggestions on what you should do...
1) Your sig says you're running 16/44.1 with an R-09 and the reason you're not running 24bit is the cost of an SD card. Bone up and buy an SD card. Heck, they cost $10 - $15 for an 4GB card which gives you 4 hours at 24/48...how much are you paying to get into the gig?
2) Set your R-09 to record at 24/48
3) Read up in the history of TS.com and figure out where unity gain is on your R-09. Set your R-09 there...don't go any higher than this setting EVER.
4) During the show, adjust the gain on the preamp upward until the lights say you can't go any higher.
5) Thats the highest levels you should go for...going higher will result in clipping either from the preamp (if you turn the gain up on the preamp higher) or from the R-09 (if you turn the gain on the R-09 higher). However, even if your levels are low (even as low as -20db can be OK), since you're recording in 24/48 you'll be getting the goods.
6) Bump levels in post...your sound should be clean.
7) If your sound isn't clean using the above sequence, email Chris Church with details...he'll tell you what your problem is because you might have another problem...something else is going on.
Option: Use Chris's upgrade program and mail in your 9000 for a 9100 upgrade for the upgrade price...I think $90.