As Ralph (I am assuming it was Ralph for Atmasphere) said, it is all in the matching- I have used tube amps since the very early 70's and have used many ARC products during that time. ( I currently use very low powered SET tube amps by Lamm, but while the amp i have is wonderful, it is not suited for all speakers). I tend to like smaller rather than bigger tube amps, in part due to the size, complexity, heat, retubing cost, etc. I'm sure that big ARC amp would be killer in the right application.
As far as tube availability goes, I buy most of my tubes from vendors over the phone/Internet, so location is not a big deal. (I don't even know of a brick and mortar store I could go to, even in NYC, to buy a tube these days).
If you are open to experimentation, and want to play around with tubes, why not experiment with a tube preamp to get started? And you could have some fun 'rolling' tubes and getting to see how different tubes affect the sound. (Just be aware, those little preamp tubes can cost much more than big power tubes, if you are buying 'new old stock' vintage tubes).
Tubes make real magic with electrostatic speakers: Quads, Martin Logans, etc. If you were willing to buy a decent pair of electrostats and a decent tube power amp, you could quickly see what tubes can do and how they differ in sound from SS. Atmasphere's amps and a good pair of electrostats would be killer. (I am currently using horns, but have two pairs of Quads, a 63 and a 57, and those are all marvelous on modest e.g. 60 watts or less tube amps- in fact i have the original Quad amps that match my Quad 57's and with 12 or 14 watts, they are a perfect match).
Today, there are some marvelous solid state amps, at least toward the top of the food chain. So, despite my long history with tube amps and preamps, I'm not advocating a 'tube is better than ss' view; again, it has to do with matching, to the speakers, to the preamp (and the source components) and ultimately, to your ears.
