The FIIO FT1 have very good stereo mismatch performance. The L/R drivers are tightly matched in weighted amplitude. There’s a bit of weighted frequency response mismatch in the L/R drivers, with a bump in the mids on the right relative to the left, which also correlates with some of the phase mismatch present across the range.
The phase response graph shown is an average with an audibility filter applied, but as these individual passes (one, two, and three) demonstrate, there are still some notable phase deviations between each side. While the peaks are larger in the treble range, these weren’t obvious during listening tests. However, the averaged phase results skirt the audibility threshold, in the mid-range particularly, and while this wasn’t noticeable during audio playback, it can potentially affect fidelity somewhat. That said, these results are only representative of our particular pair of headphones and not valid for other units.
