Your Ultra2's are a different animal than the Heritage. I found significant performance value with a solid external amp. My mid grade Denon receiver did not cut it with the Ultra2's. I had some clipping and actually blew a compression driver in one.
Darn, I wish I'd thought of that before my huge party last night. I think the DJs must have blown one of the woofers from my KL-650. It's all scratchy sounding now. I made sure it wasn't the receiver (marantz 5004), or one of the channels, by swapping cables, trying out different speakers on the same output of the receiver, swapping input signals too. Yep, sure enough, the scratchiness in the sound is a blown driver. Damn.
Worst part is, I normally drive my pair of 650 Ultra2s via my XPA-3 using the Marantz as a preamp, but when the DJs arrived and we were setting up, I lifted the amp + receiver up from the back and bent the RCA input jacks. Very weak design on the XPA-3. They got bent from the slightest pressure on the RCA cables. And don't tell me it's just "human error" because something so weak on a 60 pound, 500 dollar piece of gear is just poor engineering. I don't know who did the RCA inputs on the XPA-3, but they should be reprimanded IMO. Even a 50 dollar radio shack radio's aux-in RCA jacks are sturdier than these.
Anyway, as a result of the inputs bending, I ended up just using the receiver directly in 2.1 analog stereo mode, and now I guess one of my 650s is blown from clipping or being driven too hard from the rather weak amp of the marantz. I never intended to use it that way, especially not with blaringly loud House music blasting all night long (10+ hours at reference + levels).
Question is, what do I do to fix it? I ordered the pair online from Acoustic Sound Design for a good price, but the shipping and border duty was killer to Canada, and I really can't afford to ship it back. Does Klipsch honor warranties or do repairs from online stores? I guess I'll have to fix it myself if that's the case. Although I'm not really sure how, these things seem sealed. If anyone has any experience with this (even in terms of identifying which driver in particular was blown), I'd be very grateful.
thanks in advance.
EDIT: Moral of the story, do NOT power Ultra2's directly via any receivers that are not rated for 4 ohm operation, even temporarily. Or, do so to your own chagrin (like me and others).