Linux user here.
Not Ubuntu mind you.
Equaliser is just that. Equaliser.
If its system wide or program wide, makes small difference to me.(dont use it)
Such kind of equalisers are in software in Linux. And I am pretty sure it software adjustment in Windows too.
But you know what? Dont install linux. runn off the CD or USB and see for yourself.
with that said, linux allows you to mess with your sound card settings you did not know possible.
its NOT trivial. In fact its very hard for a nooby, as no GUI there to mess with your ALSA(pulse is using alsa, think of pulse as sound service, and ALSA as sound driver/service closer to hardware of pulse).
I tend no to use pulse at all. only exceptions - web browsers, as they dont support above 40k sample rate.
If you are there just to listen to music and movies - ALSA tweaking is your thing. Again, its NOT trivial. Pulse audio is crap solution made to make all devices to work by default.
forgot to mention. Far from "all" DACs work on Linux unfortunately. So advice to try Linux before installing it is even more important. Most installers come with "try without installing" option. If sound works there - it will 99% work in installed version too.(there is alway chance some config file will go wrong somewhere). Especially older hardware, that doesn't work on Windows may get second life on Linux.