I have a matched quad of Genalex Gold Lion KT88s that I recently purchased to try out on my new MC275. Although I can see why people like them... they are sweet and present a deep and 3 dimensional sound stage, I find I prefer the slam of the stock tubes. I am asking a very fair $140 for these tubes. That is $100 less than they sell for and I have used them no more than 200 hours.
However, I would also entertain a trade. If you boxed your original Mcintosh tubes (SED Winged C type KT88s), I will trade you straight across. Your tubes must also have less than 200 hours and test strong, however. I also have for sale a UPC-200 that I used with my MC2205 along with a Pangea power cord and a pair of REAL AudioQuest King Cobras. I would trade ALL of these items for a complete set of OEM McIntosh tubes from an MC275iv or MC275v. Again, your tubes must be Winged C type, low hours, and test strong.