Ah, fugeddaboudit
You ain't a bother. You're just going through culture shock. A lot has happpened in twenty years.
Like I said in a previous post, the "external processor loops" or "tape monitors" went the way of the dinosaur once home theatre came into play.
Those preamp outputs are generally used when one wants to use a more powerful power amp than the ones in the receiver. They really aren't designed for insertion of external devices in the circuit but, since things have changed greatly in the last 20 years, that is the onjly way equalizers and such can be used. If you really wanted to, you could insert an eq channel for each pre-out, assuming you had power amps to put on the other end, but that can get quite messy.
BTW, HT, or Home Theatre generally refers to the multi channel type stuff you just bought. Eq's do funny things to a multi-channell sound environment. They DO still make two channel stereo units, many of which can accomodate what you need, but they are rapidly fading out and generally don't mate well with HT systems.
Hang in there, guy , and welcome to the 21st century.
BTW, what speakers are you using?