"Is it just me or shared with others - 12 output tubes seem to be too many for a stereo power amp. Tube cost is quite high and more things may go wrong."
Its a legitimate concern. It really depends on the design of the amp. I don't remember all the technical details because it was a long time ago, but I had an Audio Research VT100 and had a tube go bad. It actually did damage to the amp itself, along with the bad tube. I replaced it with a VAC amp and was told that the same thing couldn't happen to the VAC because its designed differently. I would just lose the tube, and nothing else. Like I said, though, it was a long time ago and I just don't remember all the details.
Its a legitimate concern. It really depends on the design of the amp. I don't remember all the technical details because it was a long time ago, but I had an Audio Research VT100 and had a tube go bad. It actually did damage to the amp itself, along with the bad tube. I replaced it with a VAC amp and was told that the same thing couldn't happen to the VAC because its designed differently. I would just lose the tube, and nothing else. Like I said, though, it was a long time ago and I just don't remember all the details.