Phono/preamp advice for Rega RP1 needed

I am a starter to the vinyl world and bought a Rega RP1 paired with a Pro-ject Phono Box II recently. I combine them with my home theater system consisting of Pioneer VSX-921 integrated amp and Monitor Audio R270HD speakers, which turns out to be a letdown. I wonder if I'd find instant improvement by hunting some other well-reviewed phono preamp like Cambridge 640P, or I directly go for a higher budget one like Jolida JD9? Or is it mainly due to the lack of musical performance of my VSX-921 and speakers? Many thanks in advance.
You answered your own question. A H/T integrated will not do 2 channel music justice and adding a better phono pre you still wont hear its potential using the pioneer. Have you thought about a descent pre amp with H/T pass and a built in phono pre instead if you want to try and use both 2 channel and H/T with the same system?

A preamp with H/T pass and a built in phono sounds like an ideal option for me. Under a 1k budget, any suggestion?
I had a Rega Brio 3 that I loved to pieces. The built in phonstage is great for a MM cart like on the the RP1. The fellow who bought mine used it with the Rega book shelf speakers and I bet he is stoked. I had used it with Vandersteen 1C's I picked up for about $225 used. The Brio 3 was great with it. I really don't think you can go wrong with an all Rega system, though, and with the new Brio and the updated speaker lines you can pick up the older line of Brio 3 and the Rega R1 or R3 for good prices. I am a big fan of Rega and think you could do worse than to put together an all Rega system for enjoying your RP1. Just a thought. :)
My apologies. I allowed my enthusiasm for Rega to overcome me. I do think you'd be better off using something like the Brio rather than the Pioneer and playing around with a phonostage change, but have no idea about your speakers. Forget I mentioned changing speakers. I got carried away.