I agree with Reubent.
Just an added suggestion. You might first want to check the polarity of each speaker by simply connecting a 1.5V D or C cell battery across the terminals of each speaker, one at a time.
Best way to check not only the speaker but also the speaker cable for the correct polarity as a unit.
Disconnect the speaker cables from the power amp.
For the test make sure the speaker cable wires are connected to the speakers,
(+ to +) (- to -).
Pull the speaker grill from each speaker.
Take the 1.5V battery and connect the (-) wire of a speaker cable to the (-) side of the battery.
Momentary touch the (+) side of the speaker wire to the (+) side of the battery while watching the speaker drivers.
If the polarity if correct the driver cones of the speaker will move forward.
If the polarity is reversed they will pull back.
If one of the speakers is reversed polarity just change, reverse, the speaker cable connection at the speaker.
Check for the correct polarity again, just to make sure it is now correct.
Reconnect the speaker cables back to the power amp. (+ to +) (- to -)
Try your test CD......