I did an experiment with my Upton 5 string. When changing the strings to some D'Adarrio Helicore lights my trusty Sprio B broke. So I put 4 new strings on, let them settle in a bit and played a bit while monitoring the sound with a frequency analyser and a SPL meter. Then added the Helicore B and played again. Short story is that the total volume was very similar and the frequencies didn't change noticeably. I made a video of the results I'll post when I have time. This of course is one bass with one setup. Your mileage will vary.