I'm noticing that even when I have my iPhone or iPod Nano on their lowest volume level, my Image S4's still seem quite loud. I've also noticed that my Custom-1's are almost as loud too. I'm assuming this has to do with the sensitivity and impedance levels of these headphones.

 Are there any options for dealing with this problem?

  Additionally, I like the Custom-1's mid-centered sound over the darker signature of the S4, but I find that the S4 design is much more comfortable and easier to get a seal with. Therefore, I'm considering buying either the X10 or X5 to replace the S4. However, I'm worried that I might have the same problem of loud volume with the X10 or X5. I noticed that the X10 and X5 have a higher impedance (50-ohm) than the S4 (18-ohm).

Would this allow the X10 and X5 to be used at lower volumes than my S4?

Any advice would be much appreciated. Thanks!

I would buy an in line volume control if I were you.  You can get them at many mobile phone stores.  This will allow you to adjus the volume down.  The second thing is that you can adjust your iPod for maximum output.  I would think this would do the trick also.

 Thanks for the suggestions, Professor Thump. Unfortunately, adjusting the max output of the ipod has no effect in decreasing its minimum volume. I have considered getting an in-line volume control, but was concerned it might affect sound quality.

 Does anyone know if adding an in-line volume control would degrade my S4's beautiful sound?

 if I'm not mistaken, didn't you also post this question in the head-fi forum? I guess I'm just having trouble understanding what you mean by saying they're too loud at "minimum level." Wouldnt minimum level be silence? If they're "too loud" as you say, turn the volume down I guess? I just dont understand what you mean by "too loud." Is it possible you're referring to a feeling of too much treble? The S4's are definitely a bright set of earphones, that can be a bit of a shocker when moving to them from something that typically rolls off treble. My suggestion is just to stick w/ them & allow the drivers, your brain, or whatever works to burn in & get used to them. Once you get used to the sound, the S4's are amazing for the price; easily the best pair of dynamic-driver iem's I've heard south of 200 bones. 

I have the volume at "1" (which is sometimes too loud) and when I take it down one step it goes to "0" and I get no sound. I'm assuming this has to do with the S4's being very efficient and my iPhone putting out a good amount of power. The treble doesn't bother me though. I'd just like the option of dialing the volume down at times without it going completely silent.