Phono Preamp. With transformer or fully active

The Jensen Transformer website contains or used to contain some excellent white papers on transformer loading, as per the subject of Intact's and Atma's posts.  They show how and why to load down the secondaries to compensate for the effects mentioned.

Using an outboard SUT not only requires an extra pair of (expensive) ICs, it also entails passing the delicate low level signal from the cartridge through an extra pair of RCA connections (or two extra pairs, in the extreme case). The RCA plug and jack is a commercial standard but hardly a choice one would make for optimum signal transfer.  What one can do to at least partially ameliorate this problem is to hard wire the input side of the SUT to the tonearm wires.  Phono stages with built-in SUTs at least eliminate this issue.

Elliot, Not that it matters one iota to the performance of your system, but I get a reflected input impedance of 145 ohms (not 110 ohms), for your 1:18 step-up ratio into a fixed 47K ohm load resistance on your Mc phono stage.  And a step-up voltage of 5.4mV, not 6.3mV.  This is assuming that when you write "10 ohm/18X", you mean to say that you are using a 1:18 step up ratio.  Like I said, the numbers are so close that the differences don't matter, but I wonder how you made the calculations. 

For DIYers, Jensen SUTs are also excellent, and Jensen offer technical advice on how to implement them, as do EMIA.  Bob's Devices, Lundahl, Jensen, EMIA, are only a very partial list of good companies that make SUTs. Having said that, I don't own a SUT; I do own 3 high gain phono stages that can accommodate a range of MC cartridges.