Using Coverter to Add DSP effects only?

[Mancusco]

Hi - Can I use the converter to just add a DSP effect to a file, in this case Replay Gain, and keep the existing file otherwise intact?

Say it is an mp3 file, do I choose mp3 in the 'convert to' field and the same bitrate as the existing?
Then presumably 'Original Folder' to overwrite it into its current location?

Will I have to use 'Folder jpeg preserve' for the album art as well?

Thanks in advance for your help.

Sam