Here's what I do.
I use a Vox AC30CC combo (all tube) amp. When I want to use my POD XTL with the Vox, I set up a user bank with the amp modeling bypassed. This kills not only the amp emulation but the speaker cabinet emulation, mic placement, and AIR settings. So what you end up with is a very versatile multi-bank effect pedal. You also need to make sure that the "what are you connected to" setting is set up for direct-in; this turns off all the weird EQ stuff that comes into play when you are setting up to run into the front end of a guitar amp, or into a power amp.
The trick is to set the output level of the Pod so that (all of the above having been done), when all effects are turned off, the gain is the same as what it would be if you were running your guitar straight into your amp. That way, the Pod will not be pushing your amp any more than your guitar would be, and the Pod will just be buffering the guitar at unity gain when all effects are off.