The speaker quality is not just dependent on its loudness but of course it also depends on many factors like sound handling in different environment, the bass and treble, etc. In the video below which is not a scientific approach kind of a comparison, I tested four devices of Nokia just to emphasize which I prefer between these phones we we talk of audio quality on the speaker output.
Basing on my experiences with these mono speakers, I can say that Nokia N8 audio output is the best among the others. Sadly, there are no XpressMusic phones to compare, but we have the high-end multimedia phone, N97 mini, to temporarily include in our not-so-scientific test.
The result is, of course, based on the video you’ve watch and I would assist it through my own verdict that N8 is the top contender in this test, next is N97 mini, E52 and lastly the C6.