In your case preamp is acting as linear volume control. There are lots of positive things unless the input circuit isn't overdriven(which is less-likely your case) that gives enough headroom to pick up all possible details at the small signal domain and properly process it to the desired volume.
The tech specification and features of your preamp might also have maximum input voltage which may go upto 9V.
The tech specification and features of your preamp might also have maximum input voltage which may go upto 9V.