RG100G3 muddiness

[JCARROLL]

I've heard from people that if you replace the original tube in the RG100G3 it adds slightly more gain and makes it less muddy.
I haven't a clue about that sort of thing so could you tell me if it's true. If it is tell me what to buy. Thanks.

 

[RyRy2308]

I always thought it was a valve circuit and not an actual valve