If you use an SUT and you want to end up with a load of 845 ohms, you will need to use an SUT with a turns ration of 1:10 giving you 20db of gain in addition to that of your phono stage which should be at least 40dB. The resulting 60dB of gain might be enough depending on your listening habits, overall gain of your system and sensitivity of your speakers. You will then have to change the input load resistors in the phono stage from 47k to 84.5k in order to end up with an 845 ohm load.
