Both the MB-100 and the Purist are excellent product, especially the Purist. Beside great value/performance, what most people do not realize is how solidly built they are. Curt built things to last.
Personally, the Purist impressed me more than any products that I have owned to date. For $ 665.00 shipped, it has laddered stepped attennuators. Most expensive high end preamps use a pot. It also has independent dual buffered output which allow driving the subwoofer seperately without sharing with the output that drive the main amp. and other useful feature such as the pink noise generator.
I do hope that Curt will get back into audio some day (before I get too old. LOL) because he put out great products at excellent price. The fact that I still have both the MB-100 and the Purist after all these years that should tell you some thing.