I have a very similar setup.
Yes a good 2 channel amp will make a difference. Especially if you have a good 2 channel capable Pre/Pro.
I would suggest, if a new amp is the primary goal at the moment, putting all that you can torward that.
I use a Bryston 4B-ST, and for the money its hard to beat, they are known for great bass and extended highs. I would also recommend Plinius, Pass Labs, Krell, and Levinson. IMO all the aformentioned amps will surpass both the Rotel and Parasound.
My Bryston is going to stay around a while, but when it time is up, I hope to replace it with Pass Labs x350 amp.
Last but not least, Let YOUR ears do the deciding.