Pulseaudio controls wrong volume bar - Xonar DSX

I'm using Archlinux with my Xonar DSX.
My problem happens when I want to use my headphones, I just open Pulseaudio, in the Configuration tab I select the profile for analog output and so far so good. My headphones are working perfectly.

But if I want to change the volume, using Pulseaudio nothing seems to change, except for when I set volume to 0% (in this case it mutes the headphones). Using alsamixer from terminal I noticed that there are many volume columns (Master Front, Master Rear, Master Center, Master Woofer, Master Side, Headphones).
Pulseaudio is changing the Headphones column, but as I said this doesn't truly change volume output, changing Master Front does.

How can I tell Pulseaudio to bind the Master Front column instead of the Headphones one?

Thank you very much.

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