It's mentioned in [this](http://www.gibson.com/en-us/Lifestyle/ProductSpotlight/Tone-Tips/albert-king-his-10-best-422/) Gibson article that Albert King used a Roland JC120: "At that point King was living up to his already well-established legend with the help of an MXR Phase 90 phase shifter pedal (hey, it was the ’70s!) and either a Roland JC-120 or an Acoustic 270 head with an Acoustic 2x12 cabinet." He didn't use a Roland JC head it was a combo. In this article they talk about Acoustic head.more
It's a extremely clean sounding amplifier, in fact plugging into this amp will be pretty similar to a line signal with the difference that you have 2 very good speakers with great dynamic range, this makes it very usefull for effects, it is certianly more akin to high frequencies but it shows all the frequencies if you have a guitar that can reproduce them.