Created attachment 81667 [details]
...and pavumeter is right.
The attached screencast demonstrates pavumeter correctly representing the loudness, whereas pavucontrol's progressbar just stays at 100% most of the time (except when it gets really quiet during song changes).
pavumeter is actually doing some sort of log operation on the peaks output, so in a sense, pavucontrol should be "correct". It could be that what is going to your hardware is actually quite loud, and the speaker output has been kept at a relatively low volume (and hence the difference).
Locally, I see a reasonable range of output on pavucontrol while using my laptop speakers at 100% volume.