In addition to that, Questyle uses current mode amplification, which is nice for planers as planar headphones are usually current-hungry. I have listened to CMA400i/600i/800i/800R driving LCD2/3/X/XC, and I think Questyle does taps the potentials of these headphones (OPPO PM1/2 and TH500RP as well). I owned a CMA800i and really had a great time with it driving my PM-2. It appears to me that many audiophiles like the Questyle-Audeze pair, but one of the major impressions that I have, however, is that the highs of most Questyle-Audeze pairs don't sound harmonious enough. Not that they are harsh though.
In terms of pairing I'd prefer Bakoon's amplifiers with Audeze, which also make use of the current amplification. I listened to Bakoon Japan's HDA-5520, Bakoon International 's HPA-01 and HPA-21 driving some Audeze planars, and owned the HDA-5520 for some time. To me, products offered by these two brands have a strong character in general, but the pairing is very appealing. Unfortunately it probably is even harder to find a place that has Bakoon demos, but I think they are worth trying out if you see them at some shows. A problem with Bakoon Japan is that the factory set gain is usually too high for me as I listen at low volumes, and Bakoon International is way beyond my budget. They once did a Massdrop drop for HPA-01, which deters me from getting it at the MSRP.
My experience with planar headphones is that they are not easy to pair with. Most of them are current-hungry, which might be addressed by going balanced or using current amplification. But more importantly, I find the level of difficulty in finding a decent sounding combination and finding a synergistic combination similarly frustrating. I can name a number of decent sounding amplifier X-HD600/amplifier X-DT880/amplifier X-Amiron Home combinations, and a few synergistic ones, but I can't really do the for the planars I have tried. This is probably a reason why I take dynamic headphones and planars very differently. I'd be happy to take a little risk when it comes to dynamic cans, buying one that sounds OK out of any of the available demo amps and try to see how good they will match with my own stuff. But when it comes to planars, I will only seriously consider buying one if the demo combination sounds good enough.