Mcintosh C2600 preamp tube upgrade

I recently added the new McIntosh C2600 tube preamp to my system. It's paired up with the MC452 power amp along with Sonus Faber Elipsa speakers and Transparent interconnects/speaker cable.
I"m looking for some guidance with regard to upgrading the tubes in the C2600. Should I, or shouldn't I ? 
Also, what brand should I look for and where should I buy them. And finally, is this a diy upgrade or should I have it done at a audio shop? 
I appreciate any guidance all you audiophiles can offer