The VP150 would not necessarily be either louder or clearer; a lot would depend upon not only the setup but also your room and your listening habits.
Having your mains set to "small" funnels all the output below a certain frequency to the sub. Lots of people like this idea because it theoretically gives you more "headroom" (available power) from your receiver. Some other people find that with a relatively high crossover (like the typical 80Hz), they can more easily "localize" sounds at the subwoofer, which can be annoying. If you are running your mains as large, it is possible that you are generating a bit of a bump between ~50Hz and 80Hz; the frequencies that are being delivered by BOTH the sub and the mains. Some of it depends upon how your receiver handles such things. Try it both ways and decide for yourself.
Personally, I listen to music quite a bit and found that the M60's enhanced my enjoyment quite a bit. There are also legions of loyal M50 fans. Really, if you're just itching to send Axiom some more money during your trial period, you can't go "wrong". I think the sub upgrade is clearly more important than the other things. If you're happy with the M50's and don't anticipate listening to a lot of music in the future, I would get the QS8's. Personal opinion only. Worth price charged. No warranties expressed or implied. Use at your own risk. Contents may be hot.
