building the best system I can?

With your budget, go with an integrated amp. You need to decide on tubes or SS. Also assume that you will want to upgrade your speakers at some point in the future.
But first tell us if you will be using a dedicated CD player or a DAC paired with streaming music or server.
If you want a CDP, there are many good finds here on Agon.

Can't speak for anyone else, but I suggested Integrated since I thought your $5K was including a digital source. If I understand correctly, you are looking for an amp and preamp.
A McCormack amp would be an excellent choice. Then I would pair it with a tube preamp that has a low output impedance such as a Rogue. You would have power and bass slam with warm, lush sonics.

I think UnSound is saying that the first move is to match the speakers with an amp that will provide great synergy. I would agree that in a system you start with amp and speakers, after that add the preamp.
I have never heard paradigm studio 20's, so I was only stating a possible scenerio, mixing tubes with SS.

funny thing.. unsound posted at the same time as I did.

"This day and age it is very difficult to audition speakers by different manufacturers because dealers just don't carry the inventory they did 20 years ago."

That is so true, Wmbode. I want to upgrade my spkrs, but haven't yet until I find a store that carries Dali. So I say keep your studio 20's and start to build your system. In a year or two start auditioning new speakers.