Audio Do do with 40 years experience

Not my worst but kinda of funny. I downsized my office system and sold my Linn Classik which was awesome.I need cash!

So I hook up an a/d/s A2 int. amp. I am upset before I start. So I get it hooked up and no sound from the left tweeter. I switch the speaker cables around, switch the inputs and more. After an hour I determine the tweeter is blown in my Proac Tabulette 2000 speakers. Just what I need now a $ 400.00 tweeter on a pair of speakers worth $ 750.00

Wait a minute! These speakers are bi-wired. The spade on the left cable fell off when I moved the wires. The speaker was in a bad spot and I never looked at the speaker connections.
I've done worse. Put some new tubes in the CDP after removing the power to everything. Went to play it, and I heard nothing. Couldn't figure it out after checking connections, etc. Was ready to take them out, when I noticed I had not turned on the amp. Stupid, or what??!!
Milton Berle you're not.
LOL, Lindisfarne!
How about hooking up a stereo pair of subwoofers out of phase - two weeks ago - very puzzling until I went to unhook everything.

One day I turned on my tri-amplified system, started listening to music, and found the sound thin with drums and bass missing.

It took me a few minutes to notice that some how I managed to miss the bass amp because its power LED and switch were still off.