Replacement tubes for Mc C2500 & MC2301 (and a spare MC275)

[80B]

I've owned my McIntosh C2500 preamp and MC2301 monoblocks for about two years now, and while the stock tubes have a lot of life on them still, I'm inclined to swap them out and keep the stock tubes as spares. The threads here on AA are an absolute gold mine of knowledge and links to other great sources of information. Other than a Triode kit amplifier 80BJr, Boss-girl and I built when 80BJr was 12 or so, I've had no other prior experience with tubes, but fell in love with the sound of these components.

I don't intend to roll tubes often, but may do it some with my son's MC275, which is in my care for what may be a few years (), and is driving a pair of KEF LS50s for the time being.

Looks like the Gold Lions are a smart bet for the KT88s, 12AT7s and 12AX7s (gold pin variants for the preamp tubes), and I intend to get a full matched set and a spare of each, maybe skipping two 12AX7s in the C2500 since I don't use the MM phono stage. I'm also considering Siemens NOS ECC801S/12AT7s and Mullard NOS 12AT7s to roll between the MC275 and C2301. The way my C2500 and MC2301s are racked doesn't make it super-convenient to open and swap tubes, so I'm really looking to settle on something for the life of whatever I buy, but open to playing with the 12AT7s in the MC2301s becuse NOS tubes here are relatively affordable and there are only four of them. The fact we took back my son's MC275 recently is also driving my openness to trying different brands of 12AT7s since we can move them between the two amps.

While my own ears will be the ultimate deciding factor of what I settle on as my default set, are there any other tubes you think may be worthwhile considering if you had this setup? What would have a larger impact on the sound - the line stage 12AX7s in the preamp or 12AT7s in the MC2301s?

I welcome any thoughts based on your experience, including thoughts about rolling 12AX7s vs. 12AT7s in the MC275.

Boy, this turned into a long post - thanks to those of you who made it this far!