Preamp cartridge settings

I have a preamp with the following available cartridge modes.

MM - Input impedance 47 kOhm, Gain 36,5dB
MC - Input impedance 100 Ohm, Gain 56,5dB
MC - Input impedance 220 Ohm, Gain 56,5dB

My cartridge, Ortofon X5-MC (was able to get another from Juki) has a recommended load impedance of 47 kOhm.

I currently have it at the 47 kOhm setting, and it sounds good, (I get distortion if I put it at the 100 Ohm MC setting...not tried it at 220 Ohm) but is there anything in that preamp setting other than the load impedance that is strictly for a MM cartridge?

I guess in general, are these types of settings, labeled MC or MM, more guidelines for most cartridges, and impedance load is what really matters? And high output MC cartridges kind of changed things?

>>are these types of settings, labeled MC or MM, more >>guidelines for most cartridges, and impedance load is >>what really matters? And high output MC cartridges kind >>of changed things?

Exactly!! You got it right there!

Traditionally, MM cartridges came with high output (5mV range) so the phono stage could get away with 40dB gain. Also, since the MM cartridges have high coil inductance (that's how they get their high output voltage!) what really matters in their freq. response is the load capacitance. Thus, load imp. is set to 47K & it is much less of a factor in setting the MM freq. response.
In MC cartridges, the output has been very low in comparison (0.1-0.5mV). Since these cartridges have much lower (10X lower) coil inductance, the load impedance sets their freq. response more than anything else.
However, the phono signal, whether MM or MC, needs to be RIAA equalized in the very same fashion. The equalization ckt. makes no distinction between MM or MC input.
Indeed, high output MC (2.5mV) were designed to allow people to use their MM phono stages. The moderately high output crosses the threshold from where load impedance makes a big diff. to where the load cap. makes a big diff. This has allowed many more people to enjoy MC cartridges without spending more money (over & above the cartridge) on a high gain phono stage.
So, if your X5-MC has enough output to make your 36.5dB phono stage work, then I don't see a problem there. It seems that the X5-MC is a high ouptut MC, which was designed to plug into the MM input in any case! By plugging it into the MC input you are not only going to create a massive voltage divider at the output but you are also going to create a low corner low pass filter that will kill practically the entire freq. response of the cartridge & it should sound pretty dead.
Thanks for confirmation Bombaywalla. That seemed to be the most logical answer.

My TT system is now complete, at least for the time being!, and it is sounding good to me.

Rega Planar 2
Planar 2 motor upgrade
RB250 w/Expressimo tonearm wire upgrade
JA Michell Techno Counterweight
Ortofon X5-MC
Project Phono Box SE