To answer your questions, yes 6SN7s, are tubes. They will last up to 10,000 hrs depending on the circuit, but you can figure about 5,000 in normal use. This particular tube is very easy to find since they are still currently produced. The better ones IMHO are the older ones, which among OS/NOS tubes, are probably the easiest to still find at reasonable prices. That pre only takes 2 of them.
I strongly agree with the posts recommending an upgrade to a better integrated. I got sidetracked by the conversation and your original request for a pre. Getting a better integrated amp makes alot of sense. If you are curious about an integrated tube amp, there are plenty, albeit Chinese, that you can afford, especially if you buy used. My personal predjudice is to go with tube gear, I love it and think the hassles are overstated.
I strongly agree with the posts recommending an upgrade to a better integrated. I got sidetracked by the conversation and your original request for a pre. Getting a better integrated amp makes alot of sense. If you are curious about an integrated tube amp, there are plenty, albeit Chinese, that you can afford, especially if you buy used. My personal predjudice is to go with tube gear, I love it and think the hassles are overstated.