Larry, quite a few companies make separate graphic or parametric equalizers, such as the Rane PE-17. The Rane site has an interesting collection of technical papers on equalizers and other audio matters. One problem is that still more equipment is necessary to measure and attempt to correct the frequency response. The most practical route, and possibly a coming thing, is a receiver with built in microphone and equalization circuitry for all channels. Sushi's Pioneer 45TX has it, the new Yamaha 2400 and 1400 coming out early next month have it, and the usual rumors are around about other makers adopting the feature. At least now these receivers don't have the flexibility of adjustments that separate equipment offers, but it's built in and automatic.
