there's another thread by user "cuballs2" on here (can't post link, thread title "Inuke nu6000DSP fan direction results") where he did some tests and determined it runs a little cooler if you reverse the fans to pull air out. He had power cycles with the Noctua fans in the default blowing position. It's worth a shot. Also you didn't really mention where you have your amp. I'm guessing not a rack since you're annoyed enough to replace the fans. Is it in an "entertainment center", or on top of/below other equipment?