Originally Posted by: Tele Master1) What effect does the preamp have on the tone/sound/response of the guitar?[/QUOTE][font=trebuchet ms]It won't affect the guitar at all, but it affects the amp big-time![/font]

Originally Posted by: Tele Master2) Will changing the pre-amp tubes make a noticeable difference in tone/sound/response?[/QUOTE] [font=trebuchet ms]Oh, yes. The preamp is where the amp gets it's 'voice'.[/font]
[QUOTE=Tele Master]3) Can one be changed and the other 2 left alone?

[font=trebuchet ms]Yes. No wories. No adjustments to make. And you don't have to use just 12AX7 tubes. Lower gain varieties like 5751 or 12AT7 can give you more clean headroom.[/font]
[QUOTE=Tele Master]4) Does it matter which tube is replaced that effects the tone/sound/response?

[font=trebuchet ms]The first tube in the channel usually has the biggest effect. But all of them contribute - including the Phase Inverter tube that drives the power tubes.[/font]