Polk Audio RTi8.... Upgrade?

I have no idea what sort of price range you would consider.

For $1300, you could get a pair of PSB Image T6 speakers, which would be a huge upgrade IMO. If interested, you should read the Stereophile review on them. The PSB Image C4 center speaker runs $300. You can get a 20% discount or so at Saturday Audio if they have them in stock. They sell new units with minor blemishes and full factory warranty.

Another option which would be a big upgrade would be a pair of KEF Q500 speakers, which are $1100 at KEF Direct, and a KEF C6LCR center speaker is $270.

As far as a receiver is concerned, I suggest that you read the Home Theater magazine review on the Cambridge 551R. IMO (and theirs) it offers exceptionally good sound for its price. that might be a better way to go than spending the money on an amplifier.
Edited by commsysman - 12/13/12 at 11:35am

The large RTi series require a LOT of power to sound their best if you have a big space or like to listen >-10db often.

If you like how they sound but do not seem to be dynamic/punchy/loud etc... as you would like, an amp upgrade might be worth a look. If you're OK with all that then a change of speaker might be what you are looking for.

The PSB speakers are more efficient but are 6 ohms (at best) and will be a little tougher on your AVR.

And it would be best to buy from some place that has a good return or trial policy/period. Not everyone likes the same sound. Or better yet demo the speakers you're interested in.

How far away do you sit from your speakers?

They are 8ohm and 90db efficient. They are not hard to drive. I owned a pair of these for over 8 years. Honestly, for home theater there are better speakers out there for sure.