Just read this on HC -
Mixed review here. I run my tele in to a Tech 21 amp, which lacks proper mid range controls and it really cleaned up the sound. The whole blanket off the amp analogy. However...
I tried on my Traynor YCV 80Q, class tube amp A which sounds sweet to begin and it made it sound harsh and processed, completely made it WORSE. The amp has the scoop function which pretty much does same thing, anyway.
Bottom line is if you're suffering from nasal, muddy sound - like old style amp, cheap amps and humbuckers - it can really help. But if your sound is pretty crisp already don't bother. This is just a boosting equalizer with a slight delay on the lows. It's not for everyone's set up.