I am not sure that ALL Audio Note SUTs use silver-wired transformers. For those, you pay even bigger big bucks.
A SUT or any other transformer, has no inherent impedance at all. Transformers merely reflect the impedances of whatever is attached to the primaries and secondaries, as the square of the turns ratio. Thus, since most MM phono stages will present a 47K ohm resistance on the secondary side of the SUT, for a SUT that gives a 1:10 voltage gain, the cartridge will "see" 470 ohms (47K divided by 100).
Like Raul, I feel that this business about "matching" the cartridge to the SUT is a bit over-stated. You want to use a SUT that provides the voltage gain needed to drive your phono stage, and not more or less voltage gain than what is needed. After that, it is a more complex subject to talk about improving the linearity of the response by using Zobel networks, etc, around the output of the SUT. But that's not something built into any SUT I know about. Like I wrote above, in this case, 1:10 would be more than "adequate". 1:5 might even work well for the ART9, but I don't know the gain of the AN phono stage.