I can’t compare to the Questyle, but the L&P W2 has been excellent with recent low OI EE iems, including the Legend EVO. Unlike the newer W4, which I have not heard but for some reason has a much higher impedance leading to some complaints about its performance with low OI IEMs, the W2 has a very low impedance and sounded great with the EVO. I preferred it to the Lootoo paw s2 and cayin RU-6, which I also have, though those also performed well with the EVO, so your ymmv depending on your preferences. I liked the w2 because it has great drive, clean bass, and is clear and detailed, whereas the ru-6 to my ears is a bit softer around the edges—not quite as detailed. The paw s2 sounds great too—but feel the w2 edges it on technicalities, which I preferred with the evo. Can’t speak to how any of them sound with legend-x