Just to clear some point.
First, I think condenser type MIC is more than enough to measure THD. If the MIC is distorting, than the figure would only be greater not smaller.
So since I can get lower than 0.05% from one test, we should assume that the MIC's distortion is smaller than 0.05%.
Second, you mentioned that HD600's official measurement is smaller than 0.1% THD, that's true! I got even better result from it.
But please remember, it's THD with 1k sine wave! What I wanted to express is across spectrum measurements.
Since my LCD-2 is still under burning in, I didn't really recorded the measure result, just a quick test and post the impression data.
But I did have my HD600's result saved in my hard disk.
Here it is:
THD under 1k sine:
than the THD rise a little higher in lower frequency:
I didn't save lower frequency test result but it's not going to be better. On the other hand, the new LCD-2 has very consistent result from 100~2000Hz
It didn't do better with 1kHz sine wave than HD600, but just more consistent through the spectrum.
OK, I never realised distortion measurements are obtained using sinewaves. This explains why most cans measure so immaculately, in terms of the laws of physics, sinewaves are easy on inertia and g forces with a gentle acceleration rate. What is stopping you from using square waves to measure distortion? These are physically impossible to recreate. The closer we come to impossibility, the closer we come to perfection.