Run the PODxt through the FX loop. You'll have to change the values in the PODxt some but it won't interfere with the guitar input as much. That's what I did with my Triple Rectifier and my PODxt Live when I had it. There should be no reason why you shouldn't be able to get a good metal tone out of a T-verb (I have 2 and they both get great metal tones).
Now that I've said that, when I use my Tele style guitar (single coil), I don't get a good metal tone.... Any humbucker sounds beefier through a rectifier than a single coil (and this is coming from a guy that loves single coils)...... And you may not be using single coils, but I'm adding that incase you are.
Try the FX loop and PODxt and see if that works.
Thats my $.02 worth :wink: