I need some advices for the power tubes , some people think that if you're putting vintage NOS(Matched pair) tubes on the power section you will not have to adjust the bias setting...
The matched pair is a bit of a tricky one. They can be matched when they are sold, but after a burn in they do tend to wander and become not so "Matched". Some folks prefer to not match them, as matching only came into play in recent years....The old fella's never matched pairs or quads, just replaced em when they blew!Monitoring of the bias is a concearn when putting new tubes in. Sometimes you are lucky and a rebias isnt required, other times it needs to be adjusted. NOS or not, they still need to be checked for proper bias, the best sounding tubes can sound bad if not set up correctly.
For the V1 , put an original Mullard will really change the sound of my amp ?(instead of some JJ ECC83S)
Not necessarily a Mullard, but a good quality tube is the best. Think of it like a bodywork before painting a car.
If the body and initial work is wonderful, so too will be the end result. In the amps case, V1 is the first order of buisness for your signal. As was said earlier, V1 and the PI are definate places to use good quality tubes.
So yes you will notice a big difference in sound if you are currently running a cheap chinese off brand tube.
But..A good tube will help provide the strong,even, brightness and responsiveness that your amp should produce.
Cheers!