[strictly]

A bentley manual, i used to own said to test for a parstitc drain as follows ;

STEP 1) Use multi meter, in series with battery negative (i.e battery negative cable disconnected and mutlimeter connected to measure Milliamps inbetween end of cable and battery negative post) anything less than 60 milliamp was fine.

STEP 2) Use test light AFTER step 1 (no idea why) if passed both tests it was "fine"

Your stereo will suck some amps, try diconeccting that, and not every circuit is fused! do you get a big spark when you connect the neg cable back to the battery post? Can also chase it that way. Try pulling engine harness multiconnector from engine relay board, this section is largely unfused, as its power source is directly connected to the battery via the + on the starter motor

Luke