Originally Posted by Stealth
What you used has a big flaw - the preamp input is left floating ungrounded and that's the source of the pop.
stealth beat me to it!
these are both "true bypass" schemes, but the one he posted is what you want, the newer method.
the exact same thing applies to effects pedals, where the "old" wiring can cause pops and even allow the effects circuit to oscillate or otherwise induce noise while bypassed.