Before today, I had 3 iQSEs in my system. One each inside my transport and DAC, near the power transformers, and one in my Equi=Core 300 balanced PC/conditioner. I also had a spare that I was saving to use as a demonstrator on friends’ systems.
I had read here that they are not as effective for amps as front end components, but today I decided to try it on my amp. I placed it on top of the power transformer cover, with the printed side down. I wasn’t sure what to expect, but was very pleasantly surprised at how much improvement it made over the already fantastic sound I’ve been enjoying.
IME, placing one near the power transformer of any component that has one will get good results.