Technics RP-DH1200 sounding very flat

[thedotlair]

Hi peeps,

I've just got myself a steal of a deal getting a pair of Technics RP-DH1200 headphones from eBay (brand new) but have a slight problem when they are hooked up to my computer system.

I'm using the onboard sound which is part of my motherboard, which has a Realtek high-definition output on it. However when its plugged into any of the ports, the sound is rather flat but incredibly loud and its got me slightly stumped

If I plug it into my iPod nano or into a normal CD player, the sound is perfect (equalised bass output and loudness) but on the computer there is no bass at all. Now I'm hedging a guess at whether its because of a low output signal (which needs amplifying via a headphone amplifier) or I've got something configured wrong

Does anybody have any suggestions on how to remidy this situation as I've now got the headphones that I'm comfortable with, but just a lack of quality sound is annoying. If they do require amplification, any recommendations on a suitable unit would be helpful.

Kind regards
Dino