That is intentional. If you look at some of the older threads its been asked before and he said it was on purpose. Its for balancing out minor diffs in left and right, not switching them on and off. I just left mine off entirely and used a 100k DACT for vol (instead of 50k + 50k).
As far as tubes go, that is a very subjective thing, but ........
For the C series Mr Hagerman said you don't need matching tubes, but you do want matching sections (or at least close). The Clarinet uses a section from each tube for each channel instead of 1 tube per channel.
Personally I think the JJ ECC82 goldpins are a very nice new production tube, but I've not heard the JJ ECC802. For older 12AU7 tubes I've tried RCA blackplates, Amperex short plates, Mullard short plates, Brimar 13D5, and Mullard long plates (halo and square). I just got a few Telefunken smooth longplates I sniped, but haven't had time to play with them yet. So far to me the mullard long plates are the best by far. They are like the good parts of all the rest all put together. All of the tubes got ~8 hours of playing (system is in my office so its on at least 4 hours a day).
Just as a heads up about Brimar 13D5s, all 4 I've heard are VERY noisy.
If you are willing to risk eBay there are some deals out there. I picked up the Mullard long plates with square getters from Peru for around $40 compared to $100-$200. I've got a calibrated TV-10 and they all measured very very strong with plenty of life left.
I tried to get cheap versions of each "flavor" of tube so I can get a feel for the different characteristics. I figure in a few months I'll sell off the ones I don't use (and a set of backups
).
edit: Fixed the ECC83s to ECC82 (12AX7 vs 12AU7) - I picked up the wrong tube and didn't think about which number I typed.
