I have no experience with the K&K, but I do have experience with the Atma-Sphere phono.
Realize that Ralph basically built the MP-3 and MP-1 preamp as fully balanced phono preamps, and the line stage sections are bonuses. In other words, his attention to perfection is focused on the phono. That should give you some perspective, if not the comparison you seek.
Adjusting the phono's impedance loading is a simple task of attaching different resistors to the loading screws on back side of the preamp.
Also, realize that if you have RCA outputs and a ground post on your turntable, you can run balanced to the MP-3 using a pair of RCA>XLR interconnects Ralph builds specifically for this purpose. FYI, I have a set of these available if you ever decide to go the route of adding the phono to your MP-3.
Realize that Ralph basically built the MP-3 and MP-1 preamp as fully balanced phono preamps, and the line stage sections are bonuses. In other words, his attention to perfection is focused on the phono. That should give you some perspective, if not the comparison you seek.
Adjusting the phono's impedance loading is a simple task of attaching different resistors to the loading screws on back side of the preamp.
Also, realize that if you have RCA outputs and a ground post on your turntable, you can run balanced to the MP-3 using a pair of RCA>XLR interconnects Ralph builds specifically for this purpose. FYI, I have a set of these available if you ever decide to go the route of adding the phono to your MP-3.