Hate to say it ... you already have got a graphical representation of the output of the empeg in the EQ interface. Trouble is, it only says what empeg is outputting, not what your amp/speakers are delivering to you when you listen to it. It also does not give you an indication of the cumulative "envelope" that the output filters are generating for you; you just see vertical bars (no indication of Q/interaction between filter envelopes).

Short of you sampling the output with a calibrated mike and then adjusting your EQ settings to a known envelope (that you can observe from the sampling), the EQ UI tells you very little indeed.

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