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
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Yes, it's significant. The clarity, sound stage, the transparency are very well improved, but you will only noticed this after you're done breaking in your C2600
how many hours would you estimate for total break in? I'm only at about 50 hours currently and really haven't noticed any measurable change.
Mike, one last question. There are 6 tubes, right and left mm, right and left mc along with main input and main output. My only source equipment is a mcd550 CD player, so do I only replace the main input and output? And I assume I would use the gold lion?