First you'd need one of these -
http://www.amazon.com/American-Recorder-Technologies-Sound-Pressure/dp/B000I4ZVHU/ (that is the exact model I use)
For IEMS
Now download and load onto the DAP test tones (I use this site -
http://onlinetonegenerator.com/) - I have a 300 Hz tone, a 1kHz tone and a 3kHz tone - but the 1kHz tone is the one I use most often.
Set your music at a comfortable listening level on one DAP (using music you want to test)
Now connect the IEM to the SPL meter, and play your 1kHz test tone - record the SPL output on the meter
Unplug from the first DAP and play the same tone on the 2nd DAP. Adjust volume until the 2 DAPs match exactly at 1kHz - or within 0.1 dB
You can now switch between the two DAPs by quickly unplugging and replugging (make sure its the same track and same position on both) - and don't touch the volume level!
I connect the IEMs to the SPL meter using a small home-made rolled tube (it's just stiff paper), and the largest tips I have. The tips hold the IEMs securely. I make sure they are just touching the end of the meter. When unplugging and replugging (during the set-up) make sure you only touch the jack, and that the IEMs don't move inside the tube.
Here's a quick pick:
For full sized headphones - I keep the windsock on the SPL meter - carefully position the two earpieces around the windsock so that they essentially sandwich it - then use a rubber band to hold them together.
Then just use the same test method.
Hopefully that helps.
Paul
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