Damn, almost blew HAT or speakers.
Came from 2.45x, built myself a sweat case for the ropieexl rpi+hat. Turned it on. It updated to 2.504 and appeared in Bubbleupnp. Turned volume down to 10/100 as always. Started playing and Klabammmmmm. 100% volume.
Weird thing is also that ropieeexl now starts at 50% volume, but still blasts full force. Not eager to try it again. Can ik go back to 2.4xx with working t4u only???