Hello radio gods,
I just put in 2 blaupunkt speakers and a CD player from my old car
that was junked into the car I just bought (a '90 honda civic).

there are only 2 speakers (front left and right). the old ones in the
civic were blown so i put the blaukpunkts (50 watts) in from my old
car. the tape player in the civic also was bad so I put the Goodmans
CD player (cheap but then I don't need anything fancy) in from my last
car.

Everything seems to work, except for two problems.

1) When I accelerate and the radio is on, there's a weird high pitched
buzzing noise.

2) If I raise the volume to a higher level, the signal cuts out /
skips. It does this for radio or CD.

Perhaps related to this: I connected front left and front right
speakers correctly, but I noticed that if I connected the Pos and Neg
Rear left / right wires together (those coming out of the CD player)
that the signal from the front speakers sounded better - louder and
clearer. So I tied the wires together (rear left pos to rear left
neg, ditto for rear right). I ask forgiveness if this was a moronic
thing to do.

Anyway I'd like to fix this problem.

I have the CD player manual. It reads

Voltage: 12V
Polarity: Negative Ground Only
Speaker Impedance: 4 ohm - 8 ohm
Max Output Power: 4 * 10W MPO

thanks in advance