jafant
The Premier 12s don’t have easily user accessible 2,4,8 Ohm taps, but they are available in the design so a local dealer can apparently switch them to whatever tap you want.
They come configured for 4 Ohm taps, which makes sense because, per JA’s measurements, they seem to be essentially designed for 4 Ohm output, generating most power/least distortion at 4 Ohm. That’s no doubt why they seem to have worked so well with all sorts of lower sensitivity/harder to drive speakers I’ve owned including the Thiels. The CJs don't seem to "need" a high sensitivity or higher/even impedance load to work great.
Since my Joseph speakers are closer to 8 Ohms I did some research in to whether it made sense to have the CJs configured for 8 Ohm output.But research yielded information suggesting that it’s actually generally best to go with a 4 Ohm output if you can (and not just with the CJ tube amps). Even for tube amps that increase power output at 8 Ohms, or speakers that are 8 Ohms, apparently a 4 Ohm output will tend to yield the best accuracy and bass control. So for some amp/speaker pairings you may loose a tiny bit of power headroom, for slightly better sound out of 4 Ohm taps (and since it will likely be a mostly inconsequential amount, the overall better sound from the 4 Ohm can be the better choice). Again, since the CJ outputs the most power/accuracy at 4 Ohm, I leave it there and it works great with my Joseph speakers too.