This is called "RTA" or "Real Time Analysis". Others have discussed the idea (including in a very recent thread in the last couple of days which you missed).

The problem is that the empeg's microphone can't sample high frequencies. I think it'll cap out at about 11-12khz or something. So the adjustments would only be useful for lower frequencies.

Then there is the issue of calibrated microphones. Each mic has a different response curve that must be taken into account. Professional RTA systems have this all covered by bundling the pre-calibrated mic.

Still, within those limitations, I'd still like to see built-in RTA. That would rock.