OK yer the "doc" Will try your suggestion...Obviously :-).
Thank you.
Only odd, confusing me bit, is that the Hisss (buzzz? Virtually the Same sound as on My Fender Bassman, though it Could be Hummm ?? I'm not yet clear on the various nuisance noises) wasn't there when these valves were fresh out of their boxes. Or at least I didn't notice it.
Pesky 4play sounds satisfyingly 'fine' when with music :-)