Cartridge upgrade for $600

With respect to a MC, what about an Ortofon X5 MC? I know it comes in an ugly red body, but its got a good reputation and the output is HO MC at 2 mV. Its $550 at Needledoctor. I think this might be a better choice than a 2M Black

I was considering this choice along with the AT 150 MLX, but for the money the AT is probably the better deal. The Ortofon X5 also has a much lower compliance than the AT, which does not suit my low mass arm. But if you have a higher mass arm?

>>04-18-12: Manitunc
the 2m black is as good as any under $1000 mc cartridge you are likely to find.<<

Strongly disagree. A couple years ago I heard the 2M alongside a Dynavector (dealer disclaimer) 20XL and the Ortofon paled in comparison.

YMMV

In general, I hear a certain lack of dynamics / punch with high-output Mc cartridges, as compared to top-tier MM or MI cartridges (Grado, Garrott, Clearaudio).
I hope this helps, if dynamic range is a priority.