Phono Stage upgrade to complement Dohmann Helix One Mk 2

Pani, if you mate the FM122 with a linestage having 12-18db of gain, you’d be in a good place to drive most amplifiers with most LOMC cartridges. (At the far end of that range, you’re adding 18db of gain which would be very capable.) Or did you mean to say that the FM Acoustics linestages have about that much gain? If so, many other linestages also have gain in that range.  But a passive linestage or an active one with zero added gain need not apply.

If shopping for a current mode phono stage, my advice is to try to find out exactly what is the input impedance. You want it to be as close to zero as possible, but of course it cannot be zero, because that would represent a short circuit, like a mute switch, for the cartridge. I would look for 10 ohms or less, to take the most advantage of the current output of a LOMC. Likewise, you can estimate the current output of the cartridge by dividing its voltage output by its internal resistance. Right away this tells you that LOMCs with high-ish internal resistance, say greater than 10 ohms, are not going to work so efficiently with a current mode design. So, for one of the lowest voltage output cartridges ever made, the Ortofon MC2000, at .05mV, it has an internal resistance of 2 ohms. Thus it makes ~25 micro-amps of current. Do the calculation for other LOMCs and you will see that the MC2000 actually makes a credible amount of current. Because most have an internal resistance much higher than 2 ohms.

@clearthinker 
you are spot on of why I purchased a VDH Grail SB- excellent sonics, very low noise floor, long track record, bargain priced in used market.  I’m hoping for additional brand synergy with my VDH Colibri Grand Cru.

@drbond , you just bought one of the very best if not the best turntable on the market. There are many turntables that are much more expensive that you could have gone for so, you were also interested in value. I also assume that the Dohmann's design and the reputation of it's designer led you to the purchase. 

I look at things the same way. Here is how it goes with phono stages. All my favorite cartridges are low impedance moving coil cartridges. I am not sure why that is but, so be it. These cartridges are low output and require a very quiet phono stage with a lot of gain unless you run the cartridges in current mode then the lower the impedance the higher the gain resulting in a better signal to noise ratio. The magnetic braking on the cantilever is far less resulting in better tracking than you would get with a voltage mode phono stage. All the current mode phono stages I know of are solid state. This limits my search to solid state current mode stages. I think Rob Robinson of Channel D is a brilliant designer as I think of Mark Dohmann. If you want to spend $60,000 than the Seta L20 is IMHO the way to go. It is a great example of American ingenuity. I will not spend that much on a phono stage. I went for the Seta L Plus wired for current mode. If I wind up with a second tonearm I'll get a second one.  

I am cautious to bring this up but given the caliber of your table and arm, have you ever listened to the DS Audio.  I had a dps turntable with Schroder arm, and an Ortofon MA 90 with a Tom Evans Groove SRX +, until I heard the DS Audio.  I was stunned.  So much so that I got out of moving coil and now have Grand Master and Emm labs DS-EQ1.  The two would be the price of many hi end phono stages.  I realize you have a lot invested, and it won't lend itself to 2 arms but if you ever get the chance do listen.  I, in no way, am trying to suggest the other choices aren't great.  Best of luck

@dover 

Thanks for sharing those links.  I'll have to review them this weekend, when I have a few free moments.  

Thanks also for your recommendation of the van den Hul Grail SE+, as a current-based phono stage.  That seems to be a contender.  @kennyc also recommended that one. 

@lewm 

Thanks for bringing up a shortcoming of the FM Acoustics phono stage.  Since my pre-amplifier is Ypsilon, and I run it in the passive mode, I would need a phono stage with higher gain settings. 

@mijostyn 

Thanks for the recommendation of the Channel D Seta L20, which is another current-based phono stage.  I'll have to admit that I'm most skeptical about this one, though, as I'm not sure if it's really going to be worth the $60k, if another one for $30-40k is just as good. . . 

So far, I would have to place my leading contenders as all current-based phono stages: 
CH Precision P1

van den Hul Grail SE+

Channel D Seta L20

I really appreciate everyone's contribution to my learning experience, as I would really otherwise have no idea where to start.