I recently replaced my broken Sennheiser PC350 to a Beyerdynamic DT770 Pro 80 Ohm headphones and I've encountered a really annoying issue. Everything is too low. I can listen to it, but it's almost as if I'm on 10% of max volume. On Windows this issue isn't present at all, and is almost a little too loud on 100%. Pulseaudio settings are set to 100%, and every slider in the alsamixer are set to 100% too. If I set the volume to 150%, the sound gets too saturated and distorted. My sound chip is the Realtek ALC1150. I'm running Arch. EditAfter thinking it was solved, the issue came back but I believe I have more of an understanding of the issue now. Using the line out port, green one, works from time to time, but more often than not, using any of the other ports will output the what you'd expect from line out. In a way, the issue is resolved since if I use any other ports than the line out, the sound is working like it should. I'd rather not though as Windows doesn't output anything at all when not using line out, and there are times where linux too won't output to anything but line out. How come linux gets so confused? It's almost as if it believes the line out port is all of the other ports except for line out. 
Volume too quiet at maximum
alsa;pulseaudio;volume