I understand there is a difference. You can check the knowledge base on the SD website, as I recall this was an FAQ at one point. There is a difference with function, as the MP-2 has M/S capability and the MixPre does not. Sonically, the MP-2 was the first 2 channel pre SD made and was based directly on the original and first SD product, the mono block MP-1 single channel preamps that I use. The MP-1 is unique in the SD line being the only preamp with output transformers in addition to the Lundahl inputs. The MixPre/Shure FP24 redesigned unit differs sonically from the MP-2, and both differ from the MP-1 to my ears based on recordings I have sampled.