Well tonight I spent quite a bit of time listening to the High Wycombe GZ37 that David loaned me. It replaced, for the time being, my metal base GZ34/5AR4. I like the sound; it is nice and refined and wonderfully detailed. But I get all of that (less a slight bit of refinement) with my metal base, and the Volvo gets me more dynamics and balls. I'm lucky to be able to tube roll all these great tubes, but at the end of the day I am going back to my trusty metal base. The sound I heard last night, before swapping and letting the HW settle in for 24 hrs, was the best my system ever sounded. I'm also demoing a Synergistic Research Powercell 10 power conditioner, and that stayed in tonight, of course. (It doesn't make any sense to call a power conditioner "musical" but that's what the Powercell does. It creates a holistic presentation where every note decays naturally, every harmonic hangs just a little longer, and every space between notes and instruments is just a little more defined and yet natural. It's like each cable and cord got an upgrade.)
I now have the el cheapo TAD 5AR4's in the 36.5 (replacing the Tung Sol 5U4GB's) and will elt them settle for 24 hrs before listening tmrw night. On first listen, though, they have promise. there doesn't seem to be any real downside so far. They are a new tube set so not sure of the break-in.