Is this preamp mod to reduce gain advisable?

You might try Rothwell attenuators. My own preamp has quite a lot of gain and the Rothwells give me more room on the volume control and I think, a slightly quieter connection to my amps.

.

too little info

Are you talking about a transformer on the phono input or the power transformer but the latter doesn't make much sense?

Which preamp?

Why do you want to reduce the gain? I agree that the closer you operate any volume control to wide open the better but what is your goal?

.

RGS, thanks very much for the nice comments.

The Rothwell's that Toby suggested could very well be a good solution, if what you want to accomplish is simply a reduction in overall system gain (so that you would be using the volume control at higher positions). In that case, you could place them at the power amp inputs.

On the other hand, if what you are trying to accomplish is preventing overload of a preamp stage that precedes the volume control, I'm not sure that using them directly ahead of a transformer-coupled preamp input would provide good sonic results. I'm not certain that it wouldn't, either, but it would raise some possible technical issues that would warrant further study, and might require specific knowledge of the characteristics of the input transformer and its surrounding circuit.

Thanks very much again for your comments. Best regards,

-- Al

Thanks to everyone. This just a line-stage and headphone amp,
no phono involved. I tried the Rothwell and other add-on attenuators and didn't like them at all; they dulled the sound (but they did solve the gain issue). Just looking for finer volume adjustment for a stepped attenuator. I posted here before on this so sorry for the duplication.
Thanks everyone.