Whoa! Just tapping into this thread now and, as a Pass INT-25 owner, I would concur with the others who suggest that there could be a technical issue with your amp. Or an issue with the output of your digital front end. I have Devore O/93 speakers (at 93dB spec, much less sensitive than yours) and it'd be a rare occasion that I would ever get up to or past 50 volume with a feed from my Roon Nucleus -> Ayre QB-9 Twenty -> INT-25 playing any genre of music (and I like things loud for both rock and orchestral). And when I'm spinning vinyl with my Sota Sapphire TT & ModWright PH9.0XT providing the feed, the gain is even more significant into the Pass and 'quite loud' in my medium size room would be 40-45 on the volume setting.
Have that amp checked out. And if no issue with it's output, it's got to be a source feed problem (IMHO)
Although you haven't mentioned the size of your room and distance from speakers to listening spot, unless I missed it (?)