Looking to Upgrade 3 channel Amp to ATI, Need ideas

[Force]

I am looking at the ATI 1803 and 4003. I'm running Polk RTi A9 Fronts with CSi6 center channel. Is there any reason, other than the 4000's look awesome, that I should go with 4000 vs 1800 series. I do like the increased power of the 4003, but is it worth the extra money just to run Polks?
Thanks.

 

[AcuDefTechGuy]

I don't think the extra 20W in the 4003 (200W) is going to be noticed at all. So the 1803 (180W) is definitely more cost effective.

 

[lovinthehd]

Curious, is this just additional power over that of a receiver or do you use a pre-amp?