EAR 834P and gain

I was wondering if I could adjust the gain in my EAR 834P phono pre-amp. It currently has something like 68db of gain in the Moving Coil setting. This is too high. If I replaced the 12AX7 tubes with 5751 tubes, I would reduce the gain by 30%, but that is too much.
Here is my question... Can I replace ONE of the 12AX7 tubes with a 5751 and, as a result, drop the overall gain down to about 61db? If so, which of the 3 tubes would I choose to replace? And is it wise to mix and match these tubes?
Thanks in advance!

A reduction of voltage gain by 30% amounts only to a 3dB reduction in gain. You would end up with a gain of around 65dB.
Oh, ok!

I had a feeling I was wrong in my initial assumption, because people often substitute 5751 tubes for 12AX7's.

YOU can try a At7,that will reduce the gain to what you need.I have a brand new JJ tesla you can have,I had the same problem with my Quicksilver phono and replaced with 12au7 which might be too much reduction for you,but I think a 12at7 will be right for you.
Just a follow-up... Some research led me to find out that a 12AX7 MUST be used at V2. V1 and V3 can be rolled with a different tube type. I'm going to try a 5751 in V1, and then I might also try a 12AT7 in V1. After that, I might also play with the V3 tube.