The top rear speaker on the SRS-RA5000 doesn't output sound, or the sound from the speaker is very low

The top rear (up-firing) speaker on the rear side is for Immersive Audio Enhancement function only.

If you feel that the speaker does not output sound, or feel that the sound is lower or weaker than the other directional speakers:

• The top rear (up-firing) speaker is only used to assist the effect of creating three-dimension sound when the Immersive Audio Enhancement is ON. Due to the sound adjustment needed to make the best effect of the total sound balance, you may feel that the sound volume from this speaker is lower or weaker than the other speakers.
• When you play 360 Reality Audio music, the Immersive Audio Enhancement is compulsory set to OFF. Therefore, in this situation, the top rear (up-firing) speaker does not output sound.