Is the Ortofon Kontrapunkt A compatible with MMF-7

Bombaywally's info is good, and things are more complicated than that, Artemus 5, as there are synergy issues with preamps, amps and speakers as well. To do the calculations yourself, there's a really easy website which puts it for you on a graph, so all you have to do is add the weight of the cartridge to the tonearm, check againt the compliance, and follow the zone colours: if you're in the green, then you're OK! The website is at http://www.vandenhul.com/artpap/phono_faq.htm. Go to the very bottom of the page, you can't miss it. If you have an itch, and science says it's OK, then I say go for it! Of course, if someone out there has actually tried it, then as Bombaywalla says, that's a good thing. I'm an impulse creature.

Kontrapunkt needs much heavier arm.

>>However I also understand the idea that most people would probably not put a $600 cartridge on a $1000 TT.<<

You already know the truth, your MMF-7 is a very basic turntable that anything above a $90 mm cartridge is a waste of money. Unfortunately you have neither the arm nor the table to truly benefit from a high end cartridge.

Dkarmeli, how can you say that? The MMF7 stock comes with a Goldring Eroica, a $400 cartridge. Don't diss the table. It's a fine unit, hardly a basic TT. Not the best of the best, certainly, but pretty good.

Eh, I'm not too sure about this. I used to have the mmf7. Just sold it last month. knowing what I know now, there is no way I would invest in a $600 cartridge for the mmf7. No way.
That said. If you have $600 you are willing to invest. I would sell the mmf7 and add you $600 to your funds to buy a better TT. I sold mine, and added $450 to step up. I would never look back. Has to be one of the best things I did.