Amp or Pre-Pro / What makes a bigger sonic impact?

I have a Monitor Audio Gold Reference speaker system that I am currently running off a HK DPR-2005 receiver, which is their digital amped receiver. I just purchased a Sunfire Cinema Grand (200 x 5) amp, that I will be picking up today. For the forseable future, I will be using the HK as my pre-pro. For those of you who went down this upgrade path, did you see bigger improvements when you added the amp, or when you replaced the receiver with a true processor?

I added an amp to a HT reciever a few years ago and it didnt do too much, going to a seperate processor was a huge and imediate improovement.
in my experience, both make a huge difference compared to a receiver, but I'd give the edge to the pre-pro if I had to pick one.
The way you've put the question, the pre/pro will make a difference.
The amp should be seen in conjunction with the speakers it's driving -- not as stand alone.