I use several acoustic guitars plugged directly into the PODGO. A 12-string Ibanez, a 6-string acoustic with a direct piezo pickup, and a classical guitar also with a direct piezo pickup. I haven't had that problem.
The preset I use on the PODGO has a Studio Tube Pre with the Gain at 8.1 and the Level at 4.7, and the Sensitivity set to Line. Then comes a Deluxe Comp with the Mix at 60% and the Level at +1.2dB, followed by a reverb.
I don't use a speaker, and the effects go after the preamp. This works with all of them. When I use the nylon-string guitar, I adjust the EQ a bit with a SimpleEQ before the reverb.
I hope this is helpful.