11-bit isn’t directly supported. If you select 11-bit, a 12-bit read is done, then converted to 11-bit in software. This does work though, and you can certainly use 11-bit reads.
The reference voltage is VCC for the MCU, so it is ~3300mV. If you are basing your calculations on a 5V supply, the voltage you would calculate would be higher.
All pins that have a digital port are 5V tolerant, but will still only read up to 3.3V. Pins L14 (DAC0), L18 (A07) and R18 (A09) are analog-only and are NOT 5V tolerant. Connecting 5V to those pins will damage the Dash.
Your answer cleared up a lot of confusion… thanks for pointing out the 3.3v ref voltage. I was under the impression its 5v for the dash pro and 3.3v for the dash.