Sure - the easy way is, just turn the volume control to maximum. This has the advantage of leaving the balance control functioning, which you would otherwise lose if you upgrade the gain controls in the BeePre.
To disable the volume control, just move the wire from the wiper to the hot end - this removes the wiper contact from the signal path, turning the pot into a resistor, which you would need anyhow. It's a carbon composition resistor, which are generally thought to be very good sounding. The balance control can be disabled this way as well, if you want to. This approach is easily reversed if your needs change.