When you arm the track in any DAW, ableton, sonar, Cubase I'm taking it that input monitoring is on. the result will be that you will hear two signals at the same time, the stereo POD signal and the other signal from your DAW, in your case another mono track  which will be delayed by your latency. THis is the equivilant of adding a delay effect with a short delay under 10ms.

Depending on what driver you're using, you should have setup that if you need to use input monitoring to hear the daw effects, then you must not hear anysound until you arm the track. another setup would be a setup where latency doesn't make any difference and the sound of the pod is present always and when you arm a track it deosn't activate software monitoring.  further more in your case you armed a mono track so even if your setup was correct, in the best case scenario, you would hear a summed mono from your pod and not the actual stereo patch.

+1 DeanDinosaur

Turn off Record Monitoring in Ableton.