Good suggestion @immatthewj on contacting McIntosh. I thought about that too. In fact, the dealer that sold me the Mac told me that the previous owner had sent in his warranty registration card, so therefore, the warranty is transferrable. Again, I took his words for it. I was going to contact McIntosh to verify that. Maybe one day when I have some spare time.
Sorry for side tracking, 😀. Will still welcome any tubes recommendation for the McIntosh!
Cheers!