Now that I have replaced the Jbl with the Ultra, what should I do with the PB12? The main reason for its replacement was because it was making a "popping" noise, sometimes at loud volumes. Is it worth buying, say a, BASH 300w sub amp [$150 @ Parts Express] for it? I read it goes in relatively easy.[?] Would it complement the ULTRA in anyway? [I have my doubts;)]. Does it have any cash value "as is"?