What do Bass Boost and Surroundsound actually do?

[almix12]

Hey all, an Audio Engineer here. I have a few questions about the EQ on Spotify, specifically the Bass Boost and Surroundsound sliders. From a technical standpoint, what do they actually do? Are they reactive to the music? Meaning they would act differently depending on the song as opposed to an a standard graphical EQ which acts independently of the material one runs through it. 

Does the surround sound use some sort of stereo widening or panning effect? Which frequencies does the Bass Boost effect alter? 

 And lastly, on some but not all of my devices (LG Nexus 5 with latest Spotify build) turning on the EQ and turning either of the two bass sliders up noticably lowers the overall volume from disabling the EQ. Why is this? 

Thanks!!

Alex

[almix12]

Bump?

[almix12]

Anyone?

[9767]

I would actually really like this answered.