Unfortunately I don't have an X3 but the A63 is a warm-sounding earphone, more so than the RE-400. The reason that the RE-400 remains popular is that there's nothing else quite like it at the price point. The RE-600 is built better but there's a $250 price gap. For neutral sets around $100 you can get an Ety HF5 or a TWFK-based set like the VSonic VC1000, but these tend to be a little brighter/less warm than HiFiMan earphones. I also thought the Brainwavz R3 wasn't far behind the RE-400 in performance and it seems well-built, but I couldn't get comfortable with the design.
So I went ahead and purchased the RE-400 and am finding that I like them so far. Their particular take on the neutral character is attractive. Thanks much for the recommendation.
That being said, I have two concerns that are making me think about the possibility of getting a second pair of IEMs to supplement the RE-400: 1.) The RE-400 have held up so far, but the build quality concerns are well-documented, and 2.) When I'm exercising at the gym (and even sometimes for regular listening when I'm in the mood), I like to have a slightly warmer sound. But I would want something that also maintains excellent clarity through the midrange while adding some warmth. As a counterpoint for comparison, the Vsonic GR-99 are too warm to the detriment of clarity in the midrange to my ears.
With that in mind, I'm thinking maybe the Fidue A63 would be a nice supplement to the RE-400's for those occasions. That way I also get to run the RE-400's less hard, which hopefully will decrease the chances of build quality issues manifesting themselves. I wouldn't want to spend more than $75 on the second pair given that I won't be using them as often, and the Fidue's are located in that price range. Do you think the A63's are a good choice for this purpose?
Edited by steelglam - 5/14/14 at 9:33am