Adjust audio level of multiple clips by less than one db

I dont like compound clips. So I set the volume for every clip correctly and apply a final volume adjustment to the final mix to match loudness specification. Unfortunately I hit -22.5 db for my documentary and I need to hit -23 db in total. there is a slight tolerance but I feel better if i nail it. Is there a way to adjust the volume of multiple clips by less then 1 db? If I select relative adjustment I can only dial in full db amounts to adjust ist? How can I change everything by 0.5?

According to the FCP User Manual, if multiple clips are selected and you use the Volume slider in the audio inspector, you are supposed to be able to change the relative volumes by amounts smaller than 1 dB. I couldn't get it to work on my setup. In fact, with two clips selected in the timeline, the Volume slider is grayed out. Changing the Volume in the audio inspector by double-clicking into the "number box" makes absolute changes, so that's not a good option.

However, if you select multiple clips and then double-click the Gain audio effect it gets applied to all of the clips. You can then change the volume by -0.5 dB, which is what you wanted. 

Perhaps, someone else will have a better solution.