Hello,
Most Rega arms are set to work with Rega carts. You will probably need a shim for other carts. I know someone who did several cart changes outside of Rega. Art9, Art 1000, and a few others. You will need a shim to raise the tonearm or level the VTA. Also, I believe Rega uses Stevens instead of Berwald or Lofgren to set up there carts using all three screws. I told a buddy to remove the center screw and set it up using the two more popular methods. Someone told me that Stevens is good for the bid classical crescendos. I like Lofgren and used the Dr. Feikert to setup my turntables. I will tell you the top two carts by Rega are hard to beat but expensive to buy separate. The Alpheta3 is really nice! Tell the cart company you are going to use to tell you the millimeter size shim you will need. Also there is a two piece shim that makes install easier since you do not need to completely remove the Rega Tonearm. I hope this helped.