I'd also like to know what frequencies it's boosting...

I *think* (IIRC) that the relevant detail, and a lot of other useful stuff, is in the designer's manual (a PDF file) for the 7705 DSP that the empeg uses. This is available on the Philips Semiconductors web site. I might have a copy of this stashed somewhere if people are desperate to see it; I could post it on my web site if people are interested.

One of the few remaining Mk1 owners... #00015