Thank you @kijanki for your helpful response. Correct, that the preamp gain is 18dB, not 15dB. I don't know which position of the attenuator will represent the unity gain on my preamp. But there should be enough steps to attenuate the signal such that the amp input sees a reasonable voltage. But don't know if the usable range will be idea.
It sounds to me that if anything I may have to worry about too much gain rather than too little gain, right?
It sounds to me that if anything I may have to worry about too much gain rather than too little gain, right?