Oh man I'm sorry, Elitebook not Thinkpad.
There is indeed a bass setting on the speakers themselves -- it's at zero, the bass still sounds incredibly blown-out. These speakers worked just fine with my previous laptop.
When I plug my Logitech Z623 speakers into my brand-new HP Thinkpad 860 G9, the computer only recognizes them as headphones. I cannot figure out how to change this. The sound, when it comes out, is terrible, mostly the blown-out bass. I've tried updating all the drivers via Windows but can't...