Phono preamp or SUT for low output moving coil

sgordo, I beg to differ; a SUT has everything to do with the impedance the cartridge will see. There is a direct mathematical correlation, in fact. And the more voltage gain afforded by a SUT, the lower the impedance seen by the cartridge, which will be the input impedance of the phono stage (usually 47K ohms) divided by the square of the turns ratio (which is synonymous with voltage gain). This law of behavior can create difficulties if you want to augment the signal voltage of LOMCs with high internal resistance or low output MI types (because they have relatively very high inductance) using a SUT.

Hagerman makes a couple of different head amps to do what you need at reasonable prices and they are quiet.

What lewm explains is extremely important for people to understand if they want to use an SUT.  I had to address this problem myself when I bought my SoundSmith Hyperion and then tried it with an SUT.  I have two actually and both have 10:1 ratios for this very reason.   One of them also has the option of 5:1.  Fortunately I have found 10:1 is adequate with my phono stage.

to be a bit more precise, the SUT is a Step Up Transformer so the ratio is 1:X not X:1. That said it is indeed as Lewn stated. Take the square of the turns ratio and divide the input impedance of the phono stage to calculate what the load is on the cartridge. So a 1:10 is 10 x 10 = 100 and the typical 47KΩ divided by 100 = 470Ω

However, the main reason you have an SUT is to get enough gain, it should not be viewed as a means to achieve a desired load resistance. Much better to have a phono stage with a very input impedance like the EMIA LR (300kΩ is standard), select an SUT that gives you the desired voltage gain, and then load the primary of the SUT to get the desired load resistance.

Despite what others may tell you... SUTs are a superb way to get wonderful sound if you know how to implement them

Another point is the unfounded obsession with a perfect RIAA response. The idea that the RIAA has to be perfect is ridiculous given all of the other variables in frequency response in any system including the room. Why obsess with .01dB of accuracy with the RIAA when other factors give deviations in response many  orders of magnitude greater? All else equal then yes it should be as good as you can make it, BUT nothing else is ever equal so relax and go with the music. Go with what sounds the best, not measures the best. Don't chase specifications to ridiculous precision.

Agree 100% with everything @herman said!