No, you won't notice a difference in your "tone".
The rectifier tubes don't affect your tone directly. They function to convert AC power from an outlet to DC power that the amp uses to supply voltage to all the circuits. If you use this setting you may want to change them to the 5U4GB (smaller tube) for less "sag" as it reacts to incoming power.
Unless you are having some power up problems you rarely need to replace these. Never, if you use the silicone diode (solid state) rectifiers as the tube rectifiers are not in the power signal.
