Pass and ARC

@billwojo   That SP8 is certainly a classic!  Still using original power supply caps etc?  

The Pass is the surer bargain for longevity, that much is clear.

I own the XA30.5, also paired with a tube preamp (McIntosh c2500).
The pass has been in my system longer than any other piece of equipment and i consider it a "forever" amp. I don't think you'll be disappointed. I've powered several speakers with it and have settled on 94db efficient Tannoys. The amp has way more power than these speakers require. It should have no probelm powering your Klipsch.
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Synergistic would be a nice match with those. Don't see an IC right now but the Cable Co usually has some. If you need a PC there is a killer deal on SR Master Couplers https://www.audiogon.com/listings/lisa24fi-three-synergistic-research-a-c-master-coupler-power-cords... Hard to beat at $190!

Only one problem I can see with this upgrade and it may not even qualify
as a problem. But first- you do not identify what the aquisition cost of each piece would be. Post that and I may be able to offer counsel.