Isn't the cartridge called "XSV4500", not "4000"? If not, then I have learned something new. Never heard of the 4000. You've received several excellent replies to your question; I think they're all good ideas. To add to the data set on the Unitrac, this is also one of Win Tinnon's favorite tonearms. But what strikes me is that if you own a Moerch, can't you get a second arm tube for it that is medium or low mass, and just go with that? Might save money and the aggravation of mounting a second tonearm. And the DP6 with a medium to low mass arm tube will likely be at least the equal of anything else mentioned.