My DS-1 is suddenly much quieter with a "Duncan designed" humbucker, why?

A few weeks ago I got myself a Squier Jagmaster with "Duncan designed" humbuckers. It's cleans sound great and I have no issues with the volume, but when I turn on my DS-1 it's suddenly 5 decibels quieter than on cleans with my current settings, and that gap seems to increase even more with more volume on the amp. I suspected the DS-1 at first, but both a different humbucker and a single coil work just fine, so I really don't know what could be the issue. Any guesses?