Audio shows don’t tell you much, different room, different speakers. Nevertheless, they will still give you a rough idea.
I don’t know about Pass Labs. I did shortlist the INT60 for my Marten Duke 2 but got the Luxman L-590AXII instead. Initially I was having problems with the Naim / Luxman pairing (the combination sounded unnatural and a bit bright at the top) so that forced the investigation of a new amp. When the Luxman L-590AXII got into the system, everything sounded just right. There is a certain rightness to the sound as music just flows out beautifully from the speakers and with ease. Personally I find the Luxman an engaging amp, neutral with very low coloration.
I understand you currently have the L-550axii and Marten Django L. I think most here have given good advice. It is best if you can listen to both Pass and Luxman in your system with the Django L but that’s not always possible. Nevertheless, I believe you will be going forward rather than backward if you pick the 590AXII. As for the Pass Labs, nobody knows at the moment.