I've already uploaded whole W850 acoustic driver to my K800 and I did not notice significant increase of volume, but I think the sound is a bit more clear. I've also noticed that the same song is much louder (but less clear!) if you set it as ringtone and call yourself than if you just play it in media player.
So, I came up with this idea. Can we take the farfield_ring.zapf from W850's acoustic driver, rename it to farfield_play.zapf and upload it to K800?