I eventually got 7.1.4 system for my home theater. Great upgrade from my older Klipsch setup.
My current setup – L and R Arendal 1723 Tower THX and 1723 Center THX -> powered by XPA-3
L / R and LB and RB – 1723 Surround THX – powered by Outllaw 5000x
The 4 1723s heights -> powered by internal AVR amp – Denon X3700H (after changing the impedence on the AVR to 4 Ohms – I thought that wouldn’t work, but works without issues for the heights)
I have SVS PB16 for the subwoofer.
Later, I added my older Klipsch 12 inches subwoofers (stacked 1 on top of the other) – may not be the best subwoofer setup mixing them but sounds good to my ears and rumbles my seats!