A few previous posts ago, I said that the most apparent difference between first order vs. higher order is in the treble.
I also notice that first order filter speakers such as the Thiels make early 1980's recordings sounding more "musical" than they really are. I have quite a few early recordings back in the early days of digital recordings that generally sound sort of flat, analytical, and very lean with very little presence. But through first order, they actually sound musical and the sound has a fulsome quality that not there in typical conventional systems.