Quote:
Originally Posted by Aflac
..........and the iM716 has a 16ohm impedance compared to a 32ohm impedance...

I copied this from an earlier post regarding the iM716, thread: "Altec Lansing IM716 equals Ety ER4s" op, Old Dave. In short, in the HD mode the impedance is 68 Ohms.
Back for a moment to the impedance issue from earlier in this thread:
Although the interest in this topic has waned, it is an important issue that has not yet been addressed.
I pulled out my old VOM, replaced the batteries, and quickly checked the DC impedance of the iM716’s, and a couple others, as per the suggestion of gremlin. I don’t know what happens to the impedance over the frequency spectrum, sorry HeadCase.
Senn HD580: I get approx. 320 Ohms, it is rated at 300 Ohms.
Senn PMX 60: I get approx 27 Ohms, it is rated at 32 Ohms.
Sony MDRJ11G: I get approx 16.5 Ohms, it is rated at 16 Ohms.
Apple earbuds: I get approx 34 Ohms, it is rated at 32 Ohms.
So, the quickie DC readings are all pretty close to rated specs. On to the iM716:
iM716: (PCMag.com listed at 16 Ohms, mode unspecified. From my readings this may have been a missprint and is probably the iM616 which is a clone of the ER6i)
HD mode: I get approx 68 Ohms
Bass mode: I get approx 37 Ohms
Ety Research (@ 1 kHz; from their web site):
4S model: rated at 100 Ohms
4P model: rated at 27 Ohms
6 model: rated at 48 Ohms
6i model: rated at 16 Ohms
My readings were later verified by others.