Without all the name calling here's what I took about a minute to do:

Stereo preamp out: 4V, into 10K impedance
Audio panel input : 500mV, into 510ohm impedance.

Using formula :P=V^2/R I get

Stereo preamp outputs 1.6mW=2dBm
Audio panel plays full volume at .5mW= -3dBm

So we're in the ball park. You've got a little more power (about 5dB)
coming out of the preamp, but that's a a nice place to be because its
easy to lose power, hard to add it (you need to do crazy stuff like put
in amplifiers ;^) ).

Regarding formal engineering education, unless you're Dr. Weir, I win
that contest which really shouldn't be a requirement to participate in
a forum like this anyway.