The 17d mkII gets a wee bit confused at times when the musical load becomes really complex, so I really think it's a matter of finding a more suitable partner for my 20/2A which I believe is capable of much more.
I agree your rig is worth a better cartridge. It's also worth a better phono stage, which would likely provide more of the clarity you're seeking.
On the cartridge front, I've heard many that get confused just as you described. Then I heard a ZYX. Their clarity and ability to reproduce individual instruments and voices is unflappable, no matter how complex/dynamic the music gets.
I've owned the Airy 2, Airy 3 and UNIverse (in several configurations). They all maintain the clarity you're seeking. What you get as you move up the scale is increased resolution of inner detail, increased dynamics/heft/bass tightness and increased speed.
For your system and priorities I'd suggest the Airy 3 or (if at all possible) the UNIverse. The Airy 2 is rather "polite" and may not have the low end heft you're seeking. The Airy 3 is a stronger cartridge, well worth the small additional cost. The UNIverse is in another realm altogether. It's among the top handful of all cartridges being made today, and it's particularly strong in the areas you're seeking to improve. No cartridge I've heard, at any price, does a better job of portraying individual voices in the midst of wild complexities, without ever sounding analytical or unmusical.
- an Airy 3 or UNIverse on your arm would need ZYX's optional "SB" headshell weight, you'd lose dynamics and bass weight without it
- low output ZYX's are faster and more dynamic than high output ones and you should be fine with them; the quoted spec is .24mv but that's per a non-standard test record; the actual output spec comparable to Dynavector's is about .36mv
- the copper coil option is faster and more lifelike on leading edge transients, the silver coil option smooths things off slightly and provides a more relaxed sound
The Dynavector XV-1S and Transfiguration Orpheus would also be very good choices. My tastes run toward the transparency and neutrality of ZYX, particularly the UNIverse, but others prefer the slight additional oomph in the bass that those cartridges provide.
Enjoy the music whatever you choose!
Doug