Increasing a Low output MM

Now that I look more closely at the cited phono stage -- as others are saying, this Leben RS - 30 EQ is spec’d at only 23.5dB gain, which is way too low, crazy low. I personally avoid MM stages below even 40dB. However, the picture gets much more rosy if we check out Stereophile’s actual measurements of a review unit:

The RS-30EQ phono preamplifier offered a voltage gain of 37.1dB, which is very much higher than the specified 23.5dB but is appropriate for moving-magnet cartridges.

37dB is serviceable. You may still desire for extra gain when using a lower output MM or high output MC (below 2.5mV), but it’s workable. The Hagerman Piccolo I previously suggested has a lowest gain setting of 12dB which would add up to 49dB -- a bit on the high side, but could be beneficial over 37dB in certain cases.

Unfortunately when we read a bit deeper into the Stereophile article the picture gets a bit less rosy again:

The wideband, unweighted signal/noise ratio, taken with the input shorted and ref. 1kHz at 5mV, was modest, at 40.3dB left and 43.9dB right, mainly due to some residual hum components. These ratios improved to 65 and 67.7dB, respectively, when A-weighted.

That’s poor signal-to-noise performance for an MM stage, much less one on the left side of the MM gain bell-curve. Adding an active head-amp gain stage will just make this worse. You might just try the phono stage as-is and see if your line stage + amp gain can cover for it. Given the measured performance of this unit, I think it would perform best with very high output MM’s 4mV - 5mV+. I know the Ortofon 2M series has a very high output level; I don’t know of others as I mostly stick to MC’s.

Stereophile reported high overload margins for this unit, which is good -- that means it should be able to take high output MM's, or medium output MC's plus a 10x - 20x SUT ratio, without distorting. If this phono stage had low overload margins, it would have to be considered a failed product. 

Dear @mdrone  : Do it you a favor and don't put any $ on your phono stage is, is not woth to do it and a waste $.

Instead invest in a new unit as this one, please read the overall review including the measurements ( important. ):

https://www.stereophile.com/content/ps-audio-stellar-phono-phono-preamplifier

R.

@mdrone 

I am curious to lea4n, did you buy the Leben phono or end up going with another phono? 

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.