Just wanted to add my $0.02 to the conversation. I agree with others who've said something doesn't sound right when you say the Siemens CCAs sound "dark". I just installed four Siemens 1960s vintage, grey plate, silver pin, 6DJ8s in my Manley Chinook. All I can say is WOW. Their reputation is well-deserved. Siemens tubes (genuine) don't sound anything like "dark". If you can return them, that might be an option. Contact Andy at Vintage Tube Services - he stocks Siemens tubes.
My tube amp sounds darker now.
I'm using Siemens CCAs, and after putting around 100 hours on the tubes, they are almost too dark sounding now. When I first got them, after about 20 hours of use I thought the sound was a hair too bright, so I bought warm cables to offset that, and everything was perfect for awhile. But now I think the sound is too dark, and I'm about to try some different cables again.
I noticed this just after I accidently left my amp on overnight (for 12 hours). This didn't damage the tube / amp did it? Ugh, what gives?
I noticed this just after I accidently left my amp on overnight (for 12 hours). This didn't damage the tube / amp did it? Ugh, what gives?