BossAreaForum

I have a Fender Player Plus Strat HSS MN connected to 4 Boss pedals: the Boss SD-1, Boss CH-1, Boss DD-8, and the Boss IR-2 (amp/cab simulator). From the Boss IR-2, a cable goes to a DI box set to -20dB, which is then connected to the mixing desk.
When everything is connected, we get a really annoying humming noise. When we replace the pedals with a Boss GX-100, the issue is exactly the same.
Can anyone tell me how to fix this?

Welcome to the forum!

Noise is really annoying and it can have several reasons. I think we can exclude one of the single pedals from being the culprit, since the GX-100 is causing the same issues with your setup.

A first thing to check out:
What happens if you use the GX-100 only with headphones and with the same guitar? If the noise appears only with one of the longer guitar cables, then it's this cable. If it is noisy with any guitar cable, something might be wrong with the wiring of your guitar.

If it isn't noisy at all (apart from the normal single coil hum), then it's somewhere later in the chain.

I would try the guitar without the effects also, to rule out the pickups picking up noise from poor shielding. Do you ahve any dimmers in the room?

During rehearsals we don’t have any issues, but during the performance there's a terrible hum. In the meantime, I’ve bought a different power supply for the pedals — one that’s fully isolated. I’m curious to see if it will make a difference. I’ll definitely test what you suggested