It looks like after a few months of auditioning a few different IEMs I have finally found a good match to go with the X5. I am able to listen with the EQ set to normal with all files.
I tried the Cardas EM5813, Westone W50, & Grado GR10. In the end I have settled on the Westone W4r's (for now at least).
Here are the pro's & con's to each in my experience:
EM5813 - great low end, but very forward mid & rolled off high - in the end I couldn't get used to that dark signature
W50 - good, albeit slightly exaggerated low end, more balanced mid than Cardas, with rolled of high - too "muddy" sounding to me
GR10 - good low end when source material demands it, good balanced mid, great highs (mids/highs slightly forward to make the sound much brighter than the others)
I almost stopped at the Grados because the sound was much more balanced than the others, but had the W4r's recommended to me. Once I tried them the recommendation was spot on. Very nicely balanced across the spectrum, with just a bit of warmth to keep them from sounding tinny.
I'm guessing if I went to the 846's or W60's the sound would be even better dialed in to what I like (based on what I've read), but I highly doubt they will sound twice as good for twice the price. I'm trying to find a retailer near here with them so I can test them to make an informed decision.
Your mileage may vary on the remarks above, that's just what the ears on my big head heard.