iPod Classic 5.5 160Gb Euro Volume Cap
Not loud enough for what application? I'd start by trying the iPod using different headphones because volume levels can vary greatly and, using earbuds with better isolation allow for lower listening levels. 20 years down the road your ears will thank you (by not ringing in an annoying way.)

If you can't find an acceptable pair of buds consider a portable headphone amplifier like the FiiO E5. It's available for $20 or so, and won't void your warranty. 



I just realized that you specified a Euro iPod so I will also link to software that claims to remove the euro volume cap. I can't verify or guarantee it's function, I don't have ready access to Windows computer or a Euro-market iPod for testing. Do your own research and apply this patch at your own risk.