Need help calculating gain when output is expressed in dBV

[lmacmil]

The Fishman G-II acoustic guitar preamp specs are as follows:

Nominal Input Level:                   -20 dBV
Input Overload (20 Hz to 20 kHz): +8 dBV
Input Impedance:                       10 MOhm
Output Impedance:                     Less than 3.5 kOhm
Output Level:                            -20 dBV with input gain control at minimum position
                                                 -8 dBV with input gain control at maximum position
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I guess this means that at the minimum control position is gain is 1 (output the same as input).  What is the gain at the max position, i.e., how does one translate -8 dBV into a gain number?  Googling dBV leads me to believe the max gain is 4 which would be 12db.  If that is incorrect, please explain.

[CynicalMan]

dbV doesn't represent a gain. It means voltage in decibels relative to 1Vrms. So -8dbV would mean 0.398Vrms. Here's an online calculator:

http://www.sengpielaudio.com/calculator-db-volt.htm

That would mean the preamp expects an input of -20dbV (0.1V) and outputs at most -8dbV (0.398V), so the gain is 3.98.