Best position for second output jack and recommendation for stereo y cable.
Looking for recommendations for positioning of a second jack output. 20yo 12 string and I am trying to get a lyric working well in it, and if I can I may leave the M80 in it as well so I have options and can blend. Play open mics and use different PAs and have had a lot of trouble with booming/feedback in the past which may be the cheap Samick guitar ($600AU back in the 90s solid top/ ply back and sides) or problems with the installation of the previous Anthem UST not being fastened close enough. Guitar sounds nice/OK acoustically though, and sounds good when a soundman can tame it. One PA in particular was horrible.
Plenty of woodworking experience so I am happy to butcher a hole myself. Figuring the best position for a second hole is going to be at the back of the body directly behind/ under the existing jack which is in the straplock position. It would be convenient to have both holes close for use with a small stereo y cable. If anyone has any experience with this sort of setup, are there any issues that you have had, including the proximity of the lyric preamp with the M80 jack (not sure if the M80 preamp is in the jack or the soundhole pickup).
And does anyone have any recommendations for a stereo y cable barre making one myself? I have found one on the internet by Hosa but could not find others.
What other issues am I likely to have with this setup when I am letting the soundman do the blending of the 2 signals (or would I be doing most of that simply via the volume levels?). My signal normally goes straight into the PA or via a provided DI box depending on the venue.
Regards and thank you for any advice,