These were the U1s and I believe these are the px panels. The previous owner updated them.
The amp I’m using is an Anthem P5. It’s rate at 325 wpc but I’m bianping so 650 wpc. It’s an absolute beast as it’s 625 wpc into 2 ohm.
I bought it specifically for ESL speakers, I have other speakers that are much harder to drive as they dip to less than 2ohm. Anthem claims “Statement P2 and P5 amplifiers are stable into any impedance down to a short circuit at full output”. So I’m surprised they struggled with the U1s.