Best head amp of the market ?

It replaces an SUT but works differently. A pre-preamp or head amp is an active gain stage. It does not have the RIAA equalization and gain stage of a phono pre, but allows a LO MC to be plugged in to an MM phono input. An SUT is passive; it multiplies voltage according to the ratio of the windings of the primary and secondary.

The ZYX Artisan is, I think a complete phono stage (gain plus RIAA equalization). They do have a pre-pre or headamp (which I own) called a CCP-1 or something like that. It is quite good with my ZYX cart feeding the MM phono input of my VAC Ren Mk2 pre.