Since "digital" equalizers are built in to many of the Avr's and Pre-Pros today they have fallen out of favor because pretty well all of the previous models were just two channel and the poorer quality ones injected a fair amount of noise in to the audio chain.
They are still quite prevalent in stereo musical instrument applications from companies like Behringer and BBE Sound. BBE has a couple of models one of which is 32 bands per channel. The only thing you need are RCA>quarter inch adapters. I believe they are $300-400 at most and quite well built.
