Yep, ...I’d second what John says...I run a pair of Z4000’s currently.....if or when they croak, the ZW’s will be dusted off, and re-employed with TVS, and whatever modern circuit protection can be adapted......not going to be a lot of hope when the main electronics portions poop out.....I’m not on doomsday patrol, I just have back ups to deploy just in-case...😉
Pat