I’d think the X8 is a better match for the PL9.0. The X12 has more power and is 220 volt only.
It’s less weight and cost.
Until Ultra, I hadn’t heard or even seen a Studio R amp. Bassmaxx deployed a bunch of X12's
on the SP218 subs on the main stage and in the bubble. They performed as advertised and
sounded pretty good.
From what I understand, Studio R amps are designed to have a longer duration duty cycle,
much like what’s used in Meyer’s self powered speakers.
How they might compare to Thrive is unknown. What I do know is Studio R has full specifications
available and their products are readily available at reasonable cost.