rvpiano,
You have a couple choices depending on what else plugs into the preamp, and what amp you are using.
The easiest is to reduce the gain on the amplifier IF it has this option, Bryston amps have different amp gain setting, check the amp manual.
You can add an inline RCA attenuator such as Harrison Labs 6 dB RCA Line Level Audio Attenuator, Parts Express sells them, better ones are made by Russ Andrews but these are sourced UK and they do not come in 6dB. You can search inline RCA attenuators and there are a number of different forum discussions with differing results, but the Harrison are cheap. You can install the attenuators on the phono input or on the amp input depending on what else plugs into the preamp. I can't tell you which is better, I have never used them.
If you can use the attenuator on the amp input, you may want to check with CJ to see if they can mod your preamp gain from 18dB to 12dB. As a bit of a guess, also check with CJ to see IF they know if different phono tube manufacturers provide different gain.
