Hi, I have a Clapton signature Stratocaster the highest output guitar in the world. It has 140 times higher output than a Gibson Les Paul. This is because of a very powerful preamp inside the guitar. The Clapton signature Stratocaster is Run by a 9 volt battery which makes it active all the time ( it Does not work without a barrery, its got Stacked Humbuckers ( Vintage Noiseless ) Which gets 3 times more powerful as active and have 29,4 Khom in The Clapton signature Stratocaster. But its Voltage that measures output. The Clapton signature Stratocaster has an incredible 17,8 volts. A Gibson Les Paul Which is a very low output guitar has less than 0,13 volts ( lower than almost all Humbuckers ).