Bad sound in headphones but not in loudspeakers

[miguel]

I'm having troubles when trying to listen to headphones, they sound like broken, but if I disconnect them and listen to loudspeakers, they sound good.

"lspci | grep -i audio" returns:

00:03.0 Audio device: Intel Corporation Broadwell-U Audio Controller (rev 09)
00:1b.0 Audio device: Intel Corporation Wildcat Point-LP High Definition Audio Controller (rev 03)

"cat /proc/asound/cards" returns:

 0 [HDMI ]: HDA-Intel - HDA Intel HDMI
                      HDA Intel HDMI at 0xf731c000 irq 53
 1 [PCH ]: HDA-Intel - HDA Intel PCH
                      HDA Intel PCH at 0xf7318000 irq 52

I'm really a noob, this could be my first bug reported, so i don't know what more can I do.

I would appreciate any help :D