Disclaimer: This pair is owned by my greatest contributor, James.
Designed for five-long-years and finally released in 2011, ME-10EX is indeed a technical pinnacle of in-ear acoustics from Widing. Surprisingly, the Chinese manufacturer set the price of their flagship model at an eye-popping ¥ 5,000 RMB, which is roughly equivalent to $800. And with its impedance value of 130 Ω and low sensitivity in consideration, it can easily be assumed that the IEM is definitely not made for regular light users.
PRO: The sound stage is quite wide, due to reverberant bass. High frequency is well-extended up to 20 kHz as well. Such non-linear impedance characteristic shall contribute to the sound quality.
CON: Inverted polarity, inter-channel mismatch(applicable to this unit only), ringing at 4~5 kHz range, high odd-order distortion.
ON SECOND THOUGHT #1: Whether it is shallow or not, insertion depth does not play much important role with this IEM, which is a great news for users who find deep-insertion rather difficult.
ON SECOND THOUGHT #2: Interestingly, impedance decreases as the frequency rises with ME-10EX. At DC, it is around 130 Ω, and starts to decrease gradually at 1 kHz, And by 20 kHz, impedance goes down to 52 Ω. Such impedance characteristic is highly undesirable for IEM with impedance value lower than 32 Ω due to the risk of frequency dependent attenuation caused by high output impedance. However, since ME-10EX's impedance is quite high, even with a 100 Ω resistance connected in series, the resulting gain is less than -3 dB. The IEM's unusual design, in this case, shall help prevent any sensitivity loss in the frequency range over 10 kHz, which is usually caused by voice coil inductance.
ON SECOND THOUGHT #3: As expected, the acoustic output impedance of this IEM is quite high. The ringing can be dampened with additional acoustic resistance, by sacrificing the bandwidth along.
ON SECOND THOUGHT #4: As expected, the stock triflanges, or any long stemmed sleeves, definitely help taming the problematic ringing at 4~5 kHz.
ON SECOND THOUGHT #5: Since the strain relief is acoustically sealed, the side vent is the only depressurizer on ME-10EX. Blocking this hole attenuates the overall low frequency range up to 8 dB, but it is advised to leave a pinhole at least, to prevent damage of the driver.