72` and 70`Amperex Orange A-frames still burning in but I gotta say it, those who want to "tame down" highs - get Ultron PCC189 - both, white & gold labeled are less fatiguing and with smoother and more "open" highs than Amperex A-frame orange. Plus, with Ultron PCC189 you get littlebit tighter bass & kick.
Amperex GAC single leg dimple disc is littlebit better than A-frame imo, same reason as Ultrons, less
fatiguing and more smoother/open highs compared to A-frame.
But difference is not so noticeable than with A-frame vs. Ultron.
Confirmed by me too. Difference between white (marked PCC189 7ES8, with grey center plate, large O-ring getter) and gold label ultrons is almost none, if anything, gold label has tinybit more tight bass/kick but it`s very hard to notice it.