I have a v10, but the plasma, and the sound is, as you say quite flat out of the box, but there is a setting, in the plasma atleast, which i think improves things. I change MODE from 'speech' to 'music' and SURROUND from 'off' to 'v-audio surround' and the sound is actually quite good. I'm not sure what your setup is like, but I don't need anything more than this because I live in a flat where, I have a feeling, surround sound may not be appreciated/ tolerated! But if you've always used your tv's speakers, like me, then the v10 with the above changes sounds quite good.
Hope this helps, let me know how it goes.
Panasonic 42 v10/ Pioneer BDP51FD/ Xbox 360/ Samsung Virgin Vbox/ Chord HDMI Supershield/ Toshiba Satelite A131/ Panasonic phone/ 32gb iphone 3gs/60gb ipod/ Philips toaster/ Cookworks kettle/ Zanussi Washing Machine/ Zanussi Fridge/ George Foreman Grill