Customer Rating: 
Summary: Won't boost volume
Comment: Whereas this device will allow you to adjust the volume, the range is limited from no sound to the volume you'd have without it. I had gotten the [apparently mistaken] impression that it would boost the volume for headphones which had low volume for some sources (like Zune, IPod), but that does not appear to be the case. Since you can always lower the volume on the source (mp3 player, etc.), I'm having a hard time seeing the value of this device - except that in some cases it might be handier to have an inline control.
Customer Rating:
Summary: line noise removal
Comment: I have earbuds that are super sensitive to the electrical noise interference that comes from the sound source. This volume control completely removes the line noise, I am very happy.
Earbuds: EP-630
Computer: Dell 6000
Customer Rating:
Summary: A nice little gadget add-on
Comment: I bought this as an add-on gadget to a pair of headphones I recently ordered. Not sure if I needed it or not at the time of purchase, but it proved to be useful for easily controlling volume. I clipped the controller to my shirt pocket and dialed it up or down as needed, very convenient. Much better than the iPod scrolling wheel and the airplane volume dial buried on the armrest. Inexpensive gadget that works well.
Customer Rating:
Summary: handy
Comment: This is a handy and inexpensive little device. A convenient way to "tweak" your volume level. Works fine. No complaints. Like all headphone cables it doesn't like to be rolled over by chair rollers, stomped on or yanked out of the socket. If you treat it with moderate care, it ought to last for years.
Customer Rating:
Summary: works fine; I'm not sure I needed it.
Comment: The volume control was offered as an add-on with the headphones. It makes the cord longer and I don't have to fiddle with the laptop's volume control. It's useful but not one of life's necessities.
Summary: Won't boost volume
Comment: Whereas this device will allow you to adjust the volume, the range is limited from no sound to the volume you'd have without it. I had gotten the [apparently mistaken] impression that it would boost the volume for headphones which had low volume for some sources (like Zune, IPod), but that does not appear to be the case. Since you can always lower the volume on the source (mp3 player, etc.), I'm having a hard time seeing the value of this device - except that in some cases it might be handier to have an inline control.
Customer Rating:
Summary: line noise removal
Comment: I have earbuds that are super sensitive to the electrical noise interference that comes from the sound source. This volume control completely removes the line noise, I am very happy.
Earbuds: EP-630
Computer: Dell 6000
Customer Rating:
Summary: A nice little gadget add-on
Comment: I bought this as an add-on gadget to a pair of headphones I recently ordered. Not sure if I needed it or not at the time of purchase, but it proved to be useful for easily controlling volume. I clipped the controller to my shirt pocket and dialed it up or down as needed, very convenient. Much better than the iPod scrolling wheel and the airplane volume dial buried on the armrest. Inexpensive gadget that works well.
Customer Rating:
Summary: handy
Comment: This is a handy and inexpensive little device. A convenient way to "tweak" your volume level. Works fine. No complaints. Like all headphone cables it doesn't like to be rolled over by chair rollers, stomped on or yanked out of the socket. If you treat it with moderate care, it ought to last for years.
Customer Rating:
Summary: works fine; I'm not sure I needed it.
Comment: The volume control was offered as an add-on with the headphones. It makes the cord longer and I don't have to fiddle with the laptop's volume control. It's useful but not one of life's necessities.