Please correct me if I am wrong here but wasn't it proven by other pinsiders that the 3rd amp is for stereo sound, which x-files does not include stereo recordings in the roms. Or if it does maybe only one or 2 sounds? I did the research and considered this mod a few years ago and decided to go with the 2 speakers in the backbox split in mono and with the sub from pinball pro it's sounds great! I would be annoyed by only having the majority of sound in the left speaker after installing everything. I hope it works out well for you.