The XB900Ns sound fantastic for a $250 pair of wireless headphones. They're nearly on par with the 1000XM3s and Bose QC 35, and they'll make anyone feel like they're getting every penny's worth.
Where they differ in sound quality is in finer clarity. The 1000XM3s have a slightly more refined sound that enthusiasts might prefer. But if you just want your music to sound good without going over $300, the XB900Ns will suitably please.
The "XB" in the XB900N model name stands for "extra bass," and they do produce more punchy and rolling bass than a regular pair of headphones out of the box. And you can feel that extra bass, too.
They respond incredibly well to equalizer settings in Sony's headphones app, too, so you can tone down that "extra bass" if you like. The sound these headphones make can be molded to you personal preference, and Sony has plenty of presets you can easily pick from.
For example: Like the 1000XM3s, the XB900Ns don't have enough brightness and treble out of the box for my taste. I set the "treble boost" equalizer preset in Sony's headphones app for the XB900Ns, which works beautifully in harmony with the extra bass.
With that said, you may like the way the XB900Ns sound out of the box. It's up to you how you want them to sound, but the core quality is there.