Choosing the right SUT for my setup

Forget about the loading - focus on gain required.

1:10 Transformer should see 470ohms at the cartridge which is fine for either cartridge.

If your phono has reasonable gain then 1:10 should be enough.

Spend the extra and get an AU340 if you can - its much better than the AU301/320.

@jctyler Selecting the ideal ratio ?:??, is one part of the selection ratio.

SUT's have a sonic signature, I have been demonstrated quite a few models and own a few models as well.

A range from delivering a very rich, Bass Dominant through to a Hue of Rich, with a balance across the frequency range is to presented from different models.

A Head Amp is the Antithesis of the SUT, the models I have been demonstrated and compared to a SUT are Transparent as a comparison, and can be anchored to a certain range of the frequency where it is perceived as being noticeably present, or alternatively balanced across the frequency range.

It is best to learn which areas of the Cart's frequency range is wanted to be exploited or contained.

A 103r with increased richness presented through a SUT with this sonic trait, might create excessive Bass Bloom, if used through a Cabinet Speaker of a Vintage Design.       

I've never understood why someone would choose a SUT except as a temporary solution when going to LOMC from MM. I did this when I first started using LOMC. It would seem that the compromise is more than the benefit. You will have a n extra component and extra cable in the chain. Then there is the sonic signature and questionable loading. The biggest benefit is the cost which can be cheaper than a good phono preamp with enough gain for the LOMC. But even this is not set in stone. I remember the Bent SUT was around $1k some 15 yrs ago..

Considering that I don't know everything, I would be grateful for someone to tell me why I am wrong. Thanks

@artemus_5 , You are not wrong at all. I agree totally. One is much better off getting a proper MC phono stage. If you have to do a transformer it is best to install it into the phono stage or preamp. Sowter make beautiful little naked transformers for specific cartridge impedances. Installing them is a breeze. But, you are still better of with a proper MC unit. 

SUT’s do not have universal loading, meaning that just because a SUT is a 1/10 version does not necessarily mean the cartridge will see 470 ohms. Here is an example, my Jensen mc-2rr-L has a 430 ohm impedance that the cartridge will see, while my Rothwell mcx SUT, also 1/10, presents a 100 ohm loading. You need to read the specs to know what you are getting. Also, load is important as it changes the character or response of cartridge. My Hana el which requires 400 ohm or greater is used with the Jensen, my goldring eroica requires 100 ohms and is used with the Rothwell. It is also better to use a SUT for a low output m/c rather than a preamp with m/c capability. The reason being most preamps rely on j-fets to boost the signal. An SUT transformer is a passive device using only the number of wire windings to transition from lower to higher output. The transformer, if of high quality, should impart nothing to the signal.