tube amp or int for digital audio?

I have a classic Marantz 2250b receiver hooked up to my iMAC. It is driving some Energy RC-minis as our bedroom system. We use it for playing CDs, iTunes, internet radio, and watching movies.

I'm thinking of replacing the Marantz with a tube amp. I just want to try tubes! We listen to jazz, classical, new age, and some rock ... modest output levels.
Something >20 w/ch should work for us.

Since it's pretty much a 1-input system, should I go for a tube amp or an integrated-amp?

I love the look of Jolida, Cayin, Prima Luna, etc ... but have yet to listen to any.

Thx,
Rob