I think I figured it out actually. I was playing around with the config.txt file, and when I changed Preamp: -6 dB to Preamp: 6 dB (positive instead of negative) it seems to have fixed the problem.
I'm not sure why it's not attaching (I've tried a few times now, computer is being dumb or something) but... I'll just copy and paste what the config.txt document says instead. Preamp: -6 dB Include: example.txt GraphicEQ: 25 0; 40 0; 63 0; 100 0; 160 0; 250 0; 400 0; 630 0; 1000 0; 1600 0; 2500 0; 4000 0; 6300 0; 10000 0; 16000 0
I renamed it and the volume was suddenly fine! But as soon as I named it back to config the sound was super quiet again.
After I installed this, my sound quality is MUCH better so I'm very happy about that. The only problem I've had is that my volume has been greatly reduced. It used to be that having my PCs volume around 25% was more than loud enough, but now I need to put it around 75% to get to the same volume. What can I do to fix this? Thanks!