MC cart, can I use MM phono preamp?

Before you do any of the above, find out how much gain is available from your MM phono stage + linestage. Those data combined with the known output voltage of your chosen MC cartridge, usually stated in terms of millivolts (mV) measured at a frequency of 1kHz and a velocity of 3.54 or 5 cm/sec, will help you decide about a Step-Up Transformer (SUT). I agree with Amandarae, if you feel competent to solder, a SUT set-up is easy to build yourself, and you will end up with better transformers for less money. Jensen, located in SoCal, is a great company that makes excellent SUTs, and their website will tell you how to implement them to get the gain you need.

Not to take issue with the fundamental sense of Doug's post, it is in fact also true that MM cartridges are affected by loading perhaps even more so than MC types. Most importantly, because of their much higher inductance compared to an MC, MM cartridges are sensitive to capacitance. Also, I and many others have found that for really getting the most out of a top of the line MM, increasing the load R to 100K or some value in between, along with varying C, is worth the effort. If you take a look at vintage MM-only phono stages from the era prior to the obsession with MC cartridges uber alles (late 1970s to early 1980s), you will find that the best of them had adjustable loading for both R and C. It's just that the loading issues are electrically different for the two types of cartridge.