Volume control headphones- do they change the volume in the actual iPod/iPhone?

On the external volume buttons for the iPod nano 6th gen., one is jammed down and won't adjust the iPod's volume anymore = extremely aggravating since my iPod is relatively new, just over a year (weeks past warranty so I couldn't exchange).

I was told by the Apple genius that I could buy earphones that have a volume control. I researched and liked the Sony Earbuds with Volume Control. My question is if earphones likes this actually change the volume within the iPod, or if they only work best if you have your iPod preset to its highest volume?

I hope this question makes sense, because it's really valid. When I was fiddling with my iPod after it broke, I lowered the volume to very low (because the + button is broken). Would this mean the HIGHEST the volume on the earbuds would go is the volume on the iPod?

Added (1). What about this?

http://www.apple.com/...eadphones/

Since this is made by Apple, does this change the volume inside the actual iPod/iPhone?

The volume control on the earphones only affects the volume between the iPod and the earphones themselves, it does not change the volume "in" the iPod. This would only be of use to you if your iPod volume is at 100% at the moment.

If your iPod volume is stuck at 20% for example and you plug in earphones with volume control the volume of the iPod itself won't change, 100% on the earphones volume will be the same volume as the iPod is putting out, reducing the volume on the earphones will reduce the amount they play back, so setting the earphones to 50% will cut the output in half which would be equivalent of 10% of the iPod's maximum volume.

If you want to increase the volume the earphones put out beyond what the iPod is stuck at, so if the iPod is stuck at 20% and you need it to be higher then you will need a volume amplifier like this [1]

EDIT: Yea, that would work as the volume control is a remote its not actually controlling the earphones it controls the iPod. They're 20 bucks cheaper on Amazon [2] still Apple made though - just an older version but there doesn't seem to be a difference other than the price.