Worth a read even if its just for the EVH story about how he can hear the difference between cabs made of 6 or 7 ply and Eric Johnson can hear the difference between Duracell batteries and Energizers 
EVH? His reputation for tone tips and work partnership history should speak for itself. The only difference he heard was in the amount of his endorsement royalties.
As for Eric Johnson and batteries, that story has been exaggerated and changed. What he is talking about IS a real and scientifically measureable phenomena; in pedals, different types of batteries
do make them sound different. It annoys the shit outta me that no one has apparently ever brought it to his attention. Carbon or "heavy duty" batteries have different voltage drop and current capacity than alkaline batteries and it does have a sonic impact in a guitar pedal. Danelectro marketed a carbon battery for many years under the 'vintage tone' moniker. You could buy them for $9 apiece as a music store... or you could pay $1 for the same thing without the brand at any store selling 'heavy duty' nine volts.
