Sorry to hear you're not enjoying them right now. There is no question about it, the X2's have a punchy bass. I suppose this is what reviewers are referring to when they describe it as a fun
headphone. It's very dynamic and plays well with music that is similar. There are a couple of things to check first with your computers. Make sure all the Realtek enhancements are turned off. There are a lot of them and their descriptions are vague or non-existent. The X2 doesn't need any boosting in those areas and doing so could contribute to the sound you're describing. The X2's are 30 Ohm, so they are going to come off loud when paired with a high gain source, like a Sound Blaster Z, etc. Even the newer MB's have 600 ohm headphone amplifiers (20% volume for me), so your just need to use the low end of the volume scale. The smartphone will not have that issue.
While typing this, I have been listening to some Deep House tracks to try and create the situation you're describing. With my external DAC/Amp combo, I am not really hearing it. The bass is quite evident as you would expect, but it's not muddy or drowning out the other end of the spectrum. Moving the plug over to my Asus X99 on board (Realtek 1150), a lot of grain becomes quite evident. The bass does not sound as sharp and there are all kinds of things in the midrange that are making me unhappy. It's not a fair comparison between my external set up and a motherboard that in it's entirety, costs less, but that is the reality of it. THe X2's are sensitive enough to reveal other weak links. My X2's have about 70 hours of use so far.
You can try playing around a bit with the Realtek codecs if they were already off. In the DTS Ultra PC II section, try spectral enhancement with the bass off and the treble a few notches up. Normally, I don't like this kind of thing, but it's really user preference. Also, read through the review below. I am sure you've already read it, but take note of the changes he highlights after a 100 hour break-in. It may ease your concerns somewhat, or help you make a decision in a different direction.