Amp Protect help...

I traded for an amp from another member here. Part of the deal was I test the equipment prior to sending my speakers out. So I set everything up on my workbench, wire everything up, have the gains turned all the way down, stereo at 0 volume, RCA's connected, and speaker wire connected. As I begin turning the volume up, gain still at 0, the subwoofer makes a quick popping sound and the amp goes into protect.

I reset everything, check all my connections to make sure no stray wire strands are touching, check the wiring at the subwoofer, check the RCA, etc. Turn everything back on, gains still set at 0, volume at 0. As I turn the volume up it goes into protect again. I re-check everything and try two or 3 more times with the same issue.

I unhook the speakers and rca and it stays on fine, no protect.

I hook up the RCA's, turn up the volume, and no issues.

I hook up the speakers, turn up the volume and it goes into protect.

I check the impedance @ the woofer and its setting at just about .9 ohms. (Amp is 1 ohm stable)

I switch the phase and check all the settings and it still goes into protect.

Anyone have any ideas?

Battery is sitting at 12.46v and never drops.

Amp is a Arc Audio XDi 2000.1

Thanks