Prince MS

I have a sony mp70 headunit. 4 Stock speakers are connected normally.
I recently connected my subs (AudioBahn sub + amp). The gain is set to 30%-40% only.
Subs were connected to Rear Out and working fine for about 2 weeks. Then I connected it to SUBS OUT (MONO) on the unit (so I can control rear and subs independently - subs bass was over whelming at NORMAL level in headunit).

Anyway, 1 week into this setup. I was driving normal semi-high volume (at most 40% of volume) - all I hear is a "tic" and no sound coming from deck. Get the deck checked out - AMP IC is blown.

Question is - if Audio Bahn is connected through pre-ot or subs out, it was by passing the AMP in the deck. How can AudioBahn setup blow the deck? How do I fix it?

(I am using another deck with stock 4 speakers and I have been blasting it and everyfin is workin perfect)

I will post the AudioBahn models later but I think its 1200w RMS setup

Prince MS

any1?

how can pre-outs blow the amp on the deck?