I have my Pod XT Pro hooked up to my 5150ii using the 4 cable method, and everything seems to work and switch just fine ... but when I shut the FX loop off on the pod and run a clean channel into the power amp of the 5150ii, I can hear the head's lead channel bleeding through underneath the clean. It's just enough noise underneath to ruin the clean channel.
Here's how I've got it configured:
gtr > Pod gtr input
Pod fx send > 5150 input
5150 fx send > Pod fx return
Pod output > 5150 fx return
my I.O. settings are
And when I'm on the clean channel there is no clipping, no stomp box effects on, and the FX loop is off. Even if I place the entire unit in bypass it's still there. Turning the select dial all the way back to Manual Mode - still there. I've pushed and toggled every button and setting I can find or think of. If I pull the cord out of the input jack of the 5150, it goes away.
Unfortunate thing is - when I borrow my buddy's Boss GT-8 and run the exact same configuration, it works absolutely beautifully. I played my last show that way, without a hitch. That confirms to me that nothing is wrong with my head.
On a side note, I've noticed I'm also getting drastically lower volume out of the POD XT than the Boss GT-8 when running into the fx return of my amplifier. Turning the OUTPUT control to max is nowhere near loud enough, and when I crank the CHAN VOL knob, the sound of the lead channel underneath the clean stays at the same relative volume, increasing as the channel volume goes up.
I'm getting extremely irritated with this unit, and considering my HD400 gives me even WORSE problems in 4 cable method, (squealing/bleed through/soon to be on a different thread) I'm starting to think there is a fundamental flaw with the way Line 6 builds its effects loops.