Increasing a Low output MM

Just so we are all on the same page, I would not categorize the SoundSmith cartridge with an output of 2.4mV at standard velocity to be a "low output MM" cartridge. The output IS slightly lower than what one typically expects from an MM (~5mV), but there are truly low output MM cartridges that better fit the acronym, LOMM. Like the Stanton 980LZS at 0.3mV, and several others. So the situation is that we have an MM phono stage with lower than average gain, if average is greater than or equal to 40db, coupled with an MI cartridge (not even MM) that has low-ish voltage output compared to a typical MM (6db below a typical MM). Any good MM stage with a true gain of 40db (but a bit more is better) would work. You definitely should NOT need a head amp like the Marcof or any of several others (for instance Sutherland or Hagerman Picolo) for this dilemma. I agree with others who suggest replacing the Leben with a more typical MM stage that provides ideally at least 42-44db gain.

Consider a step-up-transformer. Come in various flavors, some even adjustable (Zesto). I have the latter, and gives fuller sound, though introduces a bit of transformer hum. So I have to chose between tube hiss from EAT eglow petite PS, or transformer hum from SUT. Cart is Aphelion 2 (also have a SS Zephyr, but have not mounted that on the new naia yet).

Overon. No. Don’t consider a SUT. 

Sorry. "Oberon", not "Overon". Like the character in Midsummer Night's Dream.

There are several reasons why it would not be a good idea to introduce a SUT in the OP’s system. First, most commercial SUTs offer about a 10X voltage gain. If you increase the voltage output of the OP’s cartridge by 10X, it would be ~25mV fed to the MM phono inputs. That would be more than enough to overload the circuit at least on anything approaching a transient. Second, the SoundSmith cartridge is an MI type, not an MC type for which SUTs are most suitable. MI cartridges, especially high output ones, have about 1000X higher inductance than a typical MC and thus do not do well with the net input impedance you would get if you interpose a SUT.

Mind you, the proof of the pudding is in the eating, no? I have two low output MIs (0.4mv and 1mV), and prefer them both through a SUT rather than the MC input of my phono stage.