Step-up Transformer, what's lost?

a good step-up costs pretty-much the same as a good phono $1k or higher. there could be a-bunch of different contraversal issues in this case since high-gain mc sections tend to have more than one amplification stages and/or a step-up transformer as well. also all-tube phono preamps either very costly or have not enough gain to handle super-low output cartridges.
cary audio came up with inexpencive solution and i'm sure that there are more brands that have electronic approach for a step-up that for the money is more efficient than step-up transformer.
in general for this issue i tend to partially agree with Blptwp for the MC cartridges not higher than 2mV on the output used with phono-sections 50...55dB since the coil length does affect pretty-much as amplification stages or step-up transformers.
for herron phono preamp you can use as low as 0.5mV output cartridges and mainly you need to step-up another just 6...8dB. if you go for step-up passive device you should probably research Quicksilver or EAR step-up transformers that will minimize any losses and boost the volume. Also less expencive Ortofon T1000 can just do that job. In high quality transformers you can select the gain or even use the unity gain just to match impedance with no headache. If minimal gain is used on the high quality step-up device you should hear no difference in terms of details.

G m c,
most of the times, the step up just does the trick being passive voltage amplification device connected to the minimal amplification circuit having less length of a higher gauge wire than it would be in the cartridge coil with the high output and moreover matching impedance with no additional adjustement to the load section of the phono.
MM phono-stage(especially stand-alone) coupled with step-up transformer can do about the same trick as it would the whole MC phono but and again but depending on the quality of the transformer which might be even more sophisticated to build than an electronic stage. Currently if the author uses MM version of Herron I believe that the cartridge is not properly loaded as well.
Dynavector as far as I know also produces step-up tranny with built-in set of wires. Ortofon T1000 has built-in set of wires as well. If you will order brand-new Quicksilver you can also request built-in set of wires thus you will avoid extra connection.