>>> I think a limiter would make sense, but at the price these things are turned out, I doubt they have one.<<<
They pretty much all do...well maybe not those "12"/1000w models selling for fifty bucks..
...but anything from a reputable manufacturer almost certainly will. The cost is cheap compared to dealing with a high volume of returns.
>>>Since the receiver crossover is fourth order and crossover is generally in the 60 to 80 Hz range, I doubt an Eq of the top end would add much, and if left out, I doubt you would miss it at those frequencies.<<<
I agree, not much eqing >80hz. However, there is a lot of bandwidth between 80hz and the tuning freq of a modern ported sub(usually in the 18-22hz range). Two whole octaves in fact..
>>>The Op's sub is NLA, and I bet he will have a hard time getting a replacement out of Klipsch. Unfortunately these things are designed with a disposable mentality.<<<
You could be right, I'm not sure what klipsch keeps on hand. Many manufacturers will offer a "flat" repair/replace policy though. You send in the amp and for some nominal fee(say $100) they either replace it or repair it.
Tom V.