That doesn't seem very likely to me. Unbalanced - well, compared to monitors, yes. But the "distortion" - was it objectively measured by the appropriate method or is it an "impression" given by some tonal imbalance? I'm guessing the latter option (if you didn't crank them up to max volume with a 0 dBFS input signal of course).
Its a 4" midwoofer, its going to run into limitations remarkably quickly. I didn't measure, I just noticed that the low end started to distort more than I wanted to. Just buy a 5" speaker OR high-pass it and use a subwoofer. At 96 dB the r1280t reviewed here proves my point: its a complete mess. You can reach that easily when listening to an average SPL of like 80dB.
Change the speaker wires at the amplifier side and check wether the problem stays at the left speaker or moves to the right speaker.
The measurements show high levels of low order distortion (2nd, 3rd), which is relatively hard to hear, especially at low frequencies. Drivers bottoming out are much easier to hear, more like clipping in an amplifier.
It would show up in the compression tests like those Erin does. Those show variations in frequency response at different output levels more clearly. Typically for small active speakers this will show bass levels reduced relative to higher frequencies as the output level increases, preventing the driver from exceeding its excursion limits. The more advanced forms of this take the driver's thermal characteristics into account to avoid overheating too, so results may change depending on how long it's been playing at high levels.
