Same thing happened to me. I bought a used RME ADI-2 DAC fs. I installed it and turned it on. It was set at very high volume and I immediately turned it down. Then when I played music I heard some low frequency distortion/fuzzyness/offtone. So I wondered if it was the new DAC or damaged speakers. I have Beolab 8000 powered speakers.
So for a while I turned down the bass. Some songs were great, maybe 1 in 8 were a bit fuzzy . I moved 1 speaker further from a wall. I put my ear next to the drivers to listen to songs that had fuzzy low notes. It's not definitely bad distortion, just some low bass notes are not clear.
I decided to test the tweeters. I could hear 1000 Hz, but nothing above that. My wife could hear 2000, 4000 and 8000. Is there any way to definitely test powered speakers. It's not the DAC, as using earphones sounds clear. Maybe it's bad recordings, or dId I become heightened in my listening due to the volume mishap. Or, is the new DAC clearer, so the fuzzy notes on bad recordings are noticable?