- Stop using XY; try DIN or try pointing the mics at the stacks. IMHO other than ideal situations, XY just sounds bad. YMMV.
- be sure your position is optimal (centered, ideally forward of the board, etc.)
- Use cards instead of omnis
- Familiarize yourself with your DAW software and learn to post-process what you don't like.
Remember, it's easier to take out something that's there than to put in something that's not. "Muddiness" is in the eye of the beholder and the playback system; a better mic will pick up a wider range of sound. The CA-14 is superior to the CA-11 in every way, but especially in the amount of bass it picks up.
If you just hear a lot of undefined, muddy bass, what are you listening on? If you are using a modest playback system, it may not take full advantage of what the mics are getting. Case in point - listen to any raw recording made with my DPA or Schoeps (or any other HQ full frequency range mic) on iPhone headphones or another weak system - it will sound pretty bad, or at least "muddy". On a quality system, it sounds amazing.
I would suggest trying some mild EQ first, but again, keeping a very light touch. What to you sounds like mud may to others sound like gold
))