Problem with the headphone jack

[ValentinTriesToBuildAPC]

Hey guys, I tried plugging my headphones in my case, but the sound was really bad, so I tried plugging other ones in, but the sound was always bad. Now I tried plugging my amplifier in and suddenly the sound was really great. Are my headphones just really bad, or is it a problem with the case? PS: The Headphones actually work really great with my mobile device 

[Charcoal_]

Have you tried swapping which port you plug into? (Front Panel/Mobo) Mine are better from the front panel.

[Naeaes]

Your amplifier's probably just more tolerant to interference. You see, the cable leading to the front of your case might cut close to interference sources like the power supply, fans, the GPU and so on. Even if it doesn't, the sound card itself can pickup interference from the same sources. If the cause is your sound card, the headphone jack at the back won't be any better, but if it is, keep using it or try re-routing the audio cable inside your case. Better motherboards have shielding on the audio chips (actual piece of metal glued on top of the chip and a separation gap on the PCB ). 

[Quaker]

It's probably a matter of the headphone's impedance. Your amplifier would have a relatively high impedance and put only a small load on the audio output. Your Headphones may have a relatively low impedance and the extra load causes some distortion.

Either get some higher impedance headphones/ear-buds, or use the amplifier (or a new motherboard).

[SlayerFour]

Check your front panel wiring to the motherboard.  I accidentally broke the black ground-wire on the connector to the motherboard on a recent build.  All ports sounded fantastic with exception of the front panel headphone.  Repairing the wire corrected the problem.