Quick couple questions regarding the high 10 Ohm headphone impedance:
1. I have CIEMs (5 drivers) on order. Would take a while to arrive, but when it does - how do I test whether or not they're affected by the high impedance? Would (if affected) music sound weird / off, or should I look for something specific (too much / too little bass, too much / too little something else, etc.)?
2. What about the 2.5mm balanced? I will probably order extra balanced cable (CIEMs come with 3.5mm SE) and wonder whether the balanced is also affected by high impedance or is it a SE (3.5mm) only?
Thanks.
The output impedance changes the frequency response of earphones with non-flat impedance response.
1. Technically, the sound influence of the 10 ohm OI follows the voltage division rule. To calculate the implications you need the impedance response curve of the earphones.
Let Z1 be the impedance of the earphones at 1kHz and Zf be the impedance at a given other frequency in question.
Without going into proof, the difference in dB between the response at frequency f and the response at 1kHz caused by 10 ohms of OI (taking the frequency response from a 0 ohm OI source as the reference) is
10 * log {[Zf(Z1+10)/Z1(Zf+10)]^2}
If you can't visualize that, let's just simply say that the frequency response change introduced by the OI follows the shape of the impedance curve of the earphones, i.e. high impedance frequencies are emphasized while low impedance frequencies are de-emphasized.
2. If you don't have the impedance response curve, the above meticulous equation is meaningless to you. How do the earphones sound to you? If you have 0-ohm sources to compare, by all means do a comparison. There are all kinds of impedance curves to all kinds of earphones, some start off unbalaced at 0 ohms OI and become more balanced at 10 ohms, some vice-versa. There's also the delicate question of what sounds balanced to your ears in the first place?
3. IEMatch / EarBuddy lowers the OI of the R6.
4. MSEB allows you to shape the sound beyond the one track offered by output impedance tuning.