No - that's when it's run out of power. It's slanted because it is capacitively coupledOk but I noticed through sim that as I turn the music volume up, the top and bottom of the waveform goes slanted. Is there a way to fix this with a different capacitor and/or resistor value?
Your original amplifier simulation had a completely useless 0.5VDC input offset voltage. The input capacitor blocks that DC.Also why the offset of 0.5V and amplitude of 55mV? Is that how computer speakers produce audio?
I did one that involved the use of an LM386-1 amplifier but the volume was still too low despite hearing the audio. If I can figure this amp out then I can score something better....the amplifier should be an IC or have an opamp in it.