Tube Preamp Paired with Tube Phono Stage?

My experience is as per Lewm's and Syntax. I run MC's into 47k tube preamp, Marantz 7 modded, which although it is only 60db TOTAL gain, can easily handle MC's 0.3mv up with no noise. I also had a Klyne 7 which seems to emulate tube pre's in that it is designed to run mostly 47k and use very high frequency contour filters to handle the resonances. I found 47k plus filters at around 50k plus were the go.
The Klyne has been despatched as it was easily outperformed by both the Marantz and my tweaked Theta tube preamp from the 80's.
I have generally found that the MC's with very low internal impedance such as Koetsu's ( 3 ohm ) etc run fine into 47k but have occasionally had issues with MC's with higher internal impedances such as Denon 103D ( 40ohms ) and Benz ( 40 ohms ).
I have a gut feel that the lower impedance MC's in general will do better into 47k.

Syntax,
That's a pretty bold statement that only those four phono preamps got it right given the many reputable brands out there. How many different units have your actually heard to make such a definitive finding? I'm by no means being critical of your statement, but simply curious how you reached it.

Speaking of the preamps you mentioned, do you know who distributes Klyne or how one can get more information about where you can audition one? The Klyne website has no contact or dealer information, which I find rather disappointing and unprofessional considering the target market.

Regarding the Atma-Sphere preamp, it appears there is no a stand-alone phono unit, but it's a built-in phono stage in one of the preamplifiers. Is that correct?

I'm also curious whether you heard the JC-3 preamp, which was compared favorably to the Vendetta by I believe Art Dudley in Stereophile not a long while ago. Your (and others') comments regarding the 47k ohm load also compel me to ask if this is purely a function of how good the preamp is, why do designers refer to the cartridge's design as the determinative factor, or flat out state something diametrically different? Here is a quote from the JC-3's description:
"MM 47 k ohm, MC 100 ohm or MC 47 k ohm; (MC 47 k ohm is ideal for high-end Grado moving iron cartridges)."
From the $26,000 Boulder 2008's manual:
"In the MC position, the maximum input resistance is 1,000Ω without additional components installed on the card. All four of the cards are shipped with a resistor to bring the impedance down to 100Ω, which is recommended for MC."

Are you saying Boulder claims their unit runs best at 100Ω because "they can't do it better"?

Sorry, the Boulder's retail price is actually $36,000, not $26,000. Chump change.

Actusreus, Mehran at SORAsound carries Klyne, though I don't know about his auditioning policies. Klyne preamps are very rare and hard to find. Stan Klyne builds and repairs them all by hand. He could easily grow bigger, but he doesn't care to. Hence, no, if you're looking for auditions, dealers, flavors of the month, a Klyne is not for you. They show up so rarely on the used market because once one attains a Klyne, they rarely sell them.

The Klyne 7PX 5.0 is the best phono stage that I have ever heard, tube or solid state.

Actusreus,
As far as I know the input impedance of an amplifier will have ramifications in the first gain stage with regard to bandwidth, gain etc. Therefore the chosen input impedances provided by any particular phono stage may have as much to do with the design of the succeeding gain stage as it does as with the designers choice of cartridge. No doubt many designers are trying to second guess what customers are going to buy and their preferences for loading.
It can be a chicken and egg - which comes first, cartridge or phono.
Mostly what we are buying in an analogue front end, including the phono stage, are a cocktail of complementary colorations.