I ran a series of tests to see the R-09 self noise at all the settings. This is useful info for when I record nature and acoustic shows. I hooked up a mini-plug with a 3.3k ohm resistor across each channel. Then recorded at steps of 5 gain on both inputs, and hi low settings, at 16/44.1. Here are the results after analyzing them in Har-Bal, attachments are a spectrum plot comparing line-in at 8 (approx 0 gain) and mic-lo at 30 (max) and the files are attached incase you want to analyze yourself :
Here is the Average power figures from Har-bal to compare for all the tests I ran:
Gain High Low Line
30 57.2 80.3 80.1
25 61.8 84.2 84.3
20 66.7 86.5
15 71.4 87.6
8 88.5 89.0
What this shows that is helpful for me is that running the gain switch on high increases the noise too much. So running high output mics like the AT-853 helps since they work great on line or mic low settings, both below -100db across the spectrum at 25 gain. Low and Line are almost the same noise and gain, the difference is you can get plug power on the mic-in. When using line or mic low the last steps from 25 to 30 is where you get the most added noise of 4db , so I will run at 25 or lower, line or mic low only, and add any makeup gain in post.