Actually, the gain switch is only for the XD128 but the IEM package is for all models and specifically designed for low impedance, high sensitivity IEM. Somewhere on the form they had a list of example IEMs.
Free Upgrades for Geek Wave XD 128
For those of you that have purchased the Geek Wave XD128 and have chosen to add the IEM package, we've decided to add a Gain Switch at no extra charge. Switching between pristine IEM output or powerful big-can output allows you to pair your Geek Wave with every set of headphones in your collection.
Very true but I see this as the extra mile upgrade, to get the very best possible performance. If the stock Wave 32 doesn't play nice with my iems, I'll have to declare it a severely compromised portable music player. Seriously.
LH lists the 160mW as max output at 16 ohms. I used to own the Resonessence Labs Herus, which is rated 126mW into 32 ohms. I found an online converter and it tells me this equates to 252mW at 16 ohms. If I'm using this converter correctly (someone please correct this if not true), then the stock Wave 32 and 64 will play nicer with iems than the Herus. The Herus was very good with most iems- I had the best synergy with the FitEar F111 but it did pick up hiss/noise when no music was playing. However I had no noise/hiss with the JH13 at the time. So if these max numbers are correct, I shouldn't need to spend another $128 for perfectly acceptable iem performance; however it would certainly be nice to know this for sure. (I did get the dual dac perk, so it will have a 3db lower signal to noise ratio with, further improving it's performance against the Herus).