Thank you but I don't understand what you did.
I played a signal consisting of three pure (undistorted) sine wave tones from the PC through the audio gear and JBL speakers and monitored the in-room sound at the listening position with a UMIK-1 microphone and REW software's Real Time Analysis (RTA) display at two different SPL levels, the first is not loud enough to excite much distortion in the speakers, the second, though not excessively loud, is too much for the little LBLs to handle cleanly, in response to your question above.
Where is the signal?
In Audacity.
Three pure tones of increasing frequency, combined into a single signal comprising three pure tones of increasing frequency.
I played the three tracks at the top simultaneously.
I could have played the mix track, just created now so you can see the combined signal.
What are the red curve?
Peak SPL (Sound Pressure Level) the microphone received and the RTA displayed for the displayed frequency band.
black curve?
The current SPL for all frequencies in the band monitored.
In the first video, you see (and hear) three tones, increasing in frequency. Along the bottom is the Noise Floor of the room/measurement system. The Red is a history of the Peak SPL by Frequency for that test sweep.
In the second video, you see (and hear) three tones, along with the smaller tones of Harmonic and Intermodulation Distortion Products the speaker is producing as it exceeds its comfort level, as the three Tones slowly increase in frequency. Again, the Red is a history of the Peak SPL by Frequency of that test sweep.
The Audio portion should enable you to heard the undistorted, and the distorted output of the speakers.