It has one amp behind the dash, I know this for a fact. I believe there were three types of systems. Basic, some upgraded form and Mach. I know there's an amp because I can see it and I had to bypass it when I put the radio in.
I'll look at pulling the radio to see if I can get at it. Does it help to pull out the little "cubby" below the radio as well?
1994 Mustang GT TKO 500 5 spd
Fox 75mm TB, FTI Ported Edelbrock Perf RPM, 58cc AFR 165s, FTI Cam, 4.10s, Drag Susp, PMS Tuned by Mike Post
316 RWHP & 335 RWTQ // 3,225 lbs with driver and fuel // 11.919 @ 113.92 All Motor