Phono Stage upgrade to complement Dohmann Helix One Mk 2

@drbond , I also have Sound Labs speakers, 645-8's. They are 8 foot tall speakers that are 36" wide. Yours are 40" wide. lewm also uses Sound Labs speakers. I am also waiting patiently for a Lyra Atlas Lambda SL. It seems we have similar tastes in transducers. I'll side with Lewm here. A current mode or transimpedance phono stage is the way to go. The CH Precision P1 phono stage is the one Michael Fremer uses. It is very expensive but falls within your limits. I think the finest phono stage currently available is the Channel D Seta L 20, an amazing piece of work. It is hands down the quietest phono stage ever made. It has a self charging battery power supply and will run in either current or voltage modes. I think it is $60,000. I plan on getting the Seta L plus set up for current mode operation. With an RIAA board it goes for a more reasonable $11,000. It is also battery operated but is not quite as quiet as the L20. It is not near as versatile as either the L 20 or the P1. But, I am one of those straight wire with gain people and prefer fewer switches and less wiring. Running a cartridge in current mode has one very major advantage. Cartridges are a type of generator. They produce current at a certain voltage by moving a coil in a magnetic field. Any generator can also be a motor, you just reverse the process by putting a voltage across the coils and you create a force that causes movement. Voltage across the coils of a moving coil cartridge affects the movement of the cantilever (tracking). A transimpedance phone stage has a vanishingly low input impedance thus there is very little voltage and there is little if any affect on the cantilevers movement. Tracking and the dynamic performance of the cartridge is improved. The Sutherland Phono Loco and BMC MCCI are other examples of current mode or transimpedance phono stages. The caveated is that you have to have a cartridge with a coil impedance as low as possible, certainly under 10 ohms.  Your Atlas is 7 ohms I believe. 

Dear @drbond  :  In the analog system chain I think that the phono stage perhaps is the hardest challenge for any designer/manufacturer because they have to deal with design special characterisitcs that at some time has a intrinsecal relations ship in between that is really complex to satisfy all them and the challenge is acomplish all those characteristics.

I already talked of the firs characteristic that's the inverse RIAA eq challenge the oner main phono stage characteristics are a design with high gain ( with some LOMC cartridges is need it around 80db. ) and at the same time with the third characteristic that's very low noise.

So the scenario is the worst one for all tube electronics, no one can fulfill the main phono stage targets to fulfill too the cartridge needs. No, SUT s can't do it due that are frequency bandwindth limited and develops too its own kind of " distortions ". I know that not only you but several audiophiles like the tube kind of didtortions/colorations but as with my RIAA explanation the issue is to stay truer to the recording that puts us a little near to the live MUSIC experiences. This is the target, try to mimic live MUSIC experiences, if this is not the main target of any one of you then follow doing what you did it all your life: " this is what I like it ". No problem at all.

So, the best phono stages must be SS active high gain/low noise designs. Till today no one all tube design fulfill the phono stage needs no matters what when exist some SS alternatives.

FMA and Boulder can do it even the Boulder little brother 1108. CH is an option too I listened one of its model designs and makes good job ( its top of the line goes for 90+K dollars. ).

IMHO first than all you have ( I think you already did it. with tubes.) to re-think your main system reproduction targets and go for the ones that fulfill it.

Btw, I listen the Nagra VPS in tube mode, not a unit that puts me near to the live experiences. I never had the opportunity to listen the Classic line but its measured characteristics are exactly the same as any tube phono stage:

FR: 20 Hz – 50 kHz     +0.6 dB    RIAA

Output impedance 500 ohms.

In this thread named the Audio Noote Kondo and the EMT. Both the same " history ". No one of this kind of unit designs really can honor true MUSIC. Yes, can " honor " what we like it that's a different issue.

@mijostyn  the humble BMC MCCI outperforms the Channel D at noise figures levels and its RIA deviation is beated by the FMA units and even the Boulder's. I never heard that phono stage that you like to much and I think is a good contender.

Good point from lewm, Dartzeel is other option.

No SUT's in the SS I named all high gain active designs.

R.

@rauliruegas , I think you are thinking of the Lino C which is a more entry level unit. The Seta L Plus is quieter than the Boulder and can be had with s super accurate RIAA board or it can use even more accurate digital RIAA correction through Channel D's Pure Vinyl computer program. The Seta L 20 is a really serious piece of work. Check out the specs on it. I think you will be amazed. I would love to try it but I can't get myself to spend that much on a phono stage. 

@mijostyn  : Really? No, you are wrong. As almost always I don't post almost nothing the thread gentlemans/audiophiles can't corroborate.

The L20 weigthed S/N is 88db and you can see it in the chart where Channel D made a comparisons with older Boulder models.

The BM MCCI measured by JA STEHP figures are:

"" very quiet phono preamp: its unweighted wideband signal/noise ratio, measured with the input shorted and ref. 500µV at 1kHz, was 83.2dB in the left channel, 71.8dB in the right. A-weighting these ratios gave improvements to 99.9 and 103.3dB, respectively. Channel separation was equally superb, measuring >105dB at 20kHz. "

Way better.

As I said to you:  " I never heard that phono stage ( L 20 ) that you like to much and I think is a good contender.

R.

On the issue of RIAA correction, I certainly agree that adherence to the standard curve should be tight, but my question is how tight makes any difference? Channel D claim their phono stages are within 0.1db, guaranteed, and typically within 0.01db for any given unit.  If you read the history of phono equalization, you find that the original tolerance for meeting the RIAA curve was +/-2db.  That was probably the margin for error of necessity, based on the microphones and the recording equipment up to and including the lathes available in the late 1950s. I am not sure whether that applied to making LPs or to reproducing them in the home, but it seems certain to me that most of the vintage LPs we cherish will vary by quite a bit more than +/-0.1db in their adherence to the standard curve.  So, when you're decoding one LP vs another, you can not be sure that your phono stage is correcting for the pre-emphasis put into it by the maker with the accuracy claimed. For one LP, it may be as perfect as claimed.  For another LP it may be off by much more than 0.1db.  So, I would ask for very good RIAA accuracy, but I would not choose one accurate phono stage over another based on ultra-precise adherence to the imaginary pre-empasis curve.