I'd suspect the radio wiring. Most aftermarket (and most OEM) radios have a batt+ lead (to retain station memory settings) and an ignition+ lead (to power the radio when the key is on or in ACC). If your radio dies when the dome fuse is pulled, I'll bet the ignition+ lead is wired into the dome circuit instead of a key-switched circuit.

It shouldn't pull current if you turn the radio off, but might... Good luck.