Pass Xs vs XA.8 series

I haven't heard the XS amps yet, but I own the XA100.8 amps. I upgraded from the XA100.5 and the .8 series are more dynamic and more neutral sounding, less coloration and better bass. I find them to be very well rounded and coming previously from primarily tube amps they are quite satisfying. I hope to hear the XS series someday but not sure they are worth the cost.