Indulge a newbie: To amp, or not to amp?

I recently upgraded my mains to floorstanding Mission M33i's. As my next upgrade, I'm considering an amp to power them; I've done some research, but let's talk simple. Currently, I've got a Yamaha reciever powering all 5.1 channels; what sort of actual acoustic difference am I be likely to hear by amping my mains instead? 'Signal boosting' and other terminology aside, what does amping actually mean to the quality of the sound?

I usually play movies, music, etc.. fairly loud, but not to defeaning levels, so I'm still gauging my needs.

Even a derisive snort and a link to an FAQ site would be appreciated. :)

using a 2ch amp for the mains for stereo music should give you a good improvement - cleaner sound, more impact, more separation, less congestion, more volume before it gets sounding stressed also (most receivers do this early) - do to all of these, it will sound more natural...bottom line

Thanks Psonic. :) Technical answers are easy to find online; ones like yours, less so.

Adding an amp to your 5.1 receiver via pre-outs (if this is what you are doing) will also benefit the 3 other speakers...your receiver's "burden" is lifted considerably - your receiver only has to drive 3 instead of 5 speakers...you'll notice it sound cleaner at louder volumes as well. Not a bad thing at all IMO.