That is what I had to do to take care of the same problem with my 7500.
I tried different outlets, unplugging the fridge and other electrical devices but to no avail.
I went with the CI XDC-2 and all of the problems went away.
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Epson 3500 3D projector
93" Carl's Place Flexiwhite DIY screen
Outlaw 976 Pre/Pro
Outlaw 7500 for LCR & L/R surrounds
1- Emotiva Mini X-A100 for rear surrounds
2- Outlaw LFM-1 EX subs
Oppo BDP-105 Blu-ray/DVD/SACD player
Outlaw LCR (Snell Labs) for center channel duty
Tekton Lore monitors L/R
4- Emotiva ERD-1s surround speakers
Monster HTS3600MKII power center