Sorry my post appeared multiple times. I had some odd glitch with AGon.
Are the KT150s a must? No. The stock EL34s are really nice. They have the wonderful midrange, and even the highs and lows are pretty nice. I had KT120s for a while, and they are pretty nice too, but they have an upper midrange glare that I didn't like. They added more powerful bass and crisp highs. The KT150s are the perfect balance between those tubes, and there is no hint of that KT120 glare. Is it a must? No. But, you know you will eventually try them! :-)
The idea that I could run out of power with the Premium is why I went with the HP. It has plenty of power, and I'm convinced the Premium would too. I don't have the sense of it running out of power, or "saturate" unless it's really loud, and I'd say it definitely has "slam". We rock out to it all the time.
Of your other choices, the only one I know is the Rogue. I think that it's good, but not in the same league with the PL. Build quality is good, but PL is excellent. The Rogue has a nice sound, but I find it a little edgy or glarey at times, at least by comparison. The PL sounds more refined to me, and I think it will last much longer without issues.
The Line Magnetic is one I'd like to check out. I have heard good things, and based on what I've read, i think it would be very close in performance to the PL... meaning better or worse by only a small margin. I wouldn't buy the ARC because they seem to be finicky with tubes and settings, and if a tube goes south, your amp may have to go back to Plymouth, MN for repair. That seems to be a common problem, although they sound fantastic, based on demos I have heard at the dealer.
When I was deciding what to buy, I noticed that PL is rarely for sale used. Right now, there are 6 Rogue amps for sale right here for half of retail, but only one PL set (Preamp and amp), listed at about 65% of retail. I figured that people who buy them keep them, plus they retain their value - and that's part of the reason I picked PL.
