mjb, one other thing I’d say. I have used both the KT120s and the EL34s in my PL HP. After using them for a while, I moved back to the EL34s from the KT120s. The reason is that I notice a certain midrange "glare" that's most noticable on vocals with the KT120s that I don’t hear with the EL34s. Yes, the bass is better, and extension is better with the KT120s. But, I can’t seem to get past the midrange glare. The EL34s don’t have this at all. The overall sound is a bit smoother and more pleasant.
So, that’s why I plan to move to the KT150s. From what I’ve read, they seem to be closer to the EL34 sound balance with the KT120 sparkle and punch, but without that glare. We will see, soon as I scrape my pennies together.
One other thing I forgot to mention. My listening area is about 13x13. But one wall is open to a large room, approx 30x25. So, it’s sort of an L-shaped room, with the side area set up for more critical listening. But, in the larger room, it’s plenty loud, very clear, and overall plenty of power for the space. Sounds great, and everyone loves the PL and B&W match.