Mike, you're right, this thread is all over the place.
Trust me the suhrs aren't for you but would be real useful for some things. I've got a set of VZ vintage plus, tried them briefly and they sound great but I'm holding off using them full time until I sort out all the valve/speaker changes and am happy with them which is pretty much the point I'm at now. I didn't want to mess around with too many things at once and find I'm going in completely the wrong direction. The V30's are really warming up and the depth and clarity I'm getting now is really enjoyable.
I got the KT66's biased at 35mA and wasn't sure, the amp still sounded too hot. Too compressed. So I took your advice and got them re biased @ 30 mA and find the amp really openned up, headroom and more bell like with that nice wide detailed mid range, I'm really happy with them. I thank you again.
The preamp valves that I put in, nos tungsram, have made a HUGE difference. I've heard guys on this forum talking about how the right nos tube can make your tone "bloom", well I guess this is what they must be talking about. I got a few nos ( more like used! ) preamp tubes from tubetramp and to be totally honest they didn't sound that good. The best one was an RCA but the others , brimar, telefunken and supposedly tungsram sounded harsh and crap basically, they just changed the tone so much, added so much gain and midhump that you'd have thought it was a different amp you were playing through. Put the standard issue marshall garbage in and the amp went limp and lifeless, so the tungsrams are for me.
Which brings me on to the plexi switch on the UA, Now that the V30's are not so tight and with the tungsram in v1, I finally get it! I suspect it's the tube rather than the speakers. I run my amp just the same as you with the two channels jumped just the same. Now I like the damn switch, I haven't had it on for an entire gig but when I had it sounded great, like extra prescence and a real sweet bite, a " metallic clang" as you well put it. Funny that
I would strongly reccomend trying those tungsrams, drummers have noticed

!!
I put a link to that guys ebay items that I got them from on the other thread, seems like he's got loads of stuff all the time. He was cool to deal with and the stuff arrived quickly and well packed.
Paul