Hi, the PLUS or NEO sound boards will play the same attract sound as the original factory sound board. If you want to change this attract music, you'll have to replace the music file. But it might impact the gameplay as it could be the same music used for the gameplay itself.
For information, the "PinSound attract / jukebox mode" is on my todo list. It'll allow you to define a set of sound files to be played when your pinball machine is in idle mode.