LCR phono stages we know about

Addendum. After composing that long treatise, I did some surfing to find out more about the Slagle LCR phono stage owned by my neighbor. It turns out that the phono stage is called "Emia" and is marketed by Dave and Jeffrey Jackson, in collaboration.
Here

Further, the "Kahn" Experience phono stage is also a product of this same collaboration, only it's more expensive than the Emia.

So these two would be important players in the LCR game, albeit hardly mass-market.

Lew, the Vida Aurorasound has received a bit of attention in Asian markets. Reportedly around $5K. I have not seen or heard it at the shows.

Dave, I looked it up. Not much info regarding the innards. Seems to be solid state. Does not seem to have adjustment for load R and C. However, it does have a mono switch. (I don't know how you can build a phono stage with high end pretensions and not include a mono switch.) As you know, I'm partial to tubes, but I'd like to hear this one. Do you have direct knowledge?

Audio Note UK also makes few models of phono preamps that employ LCR network.

Typical LCR network is sandwiched between two gain stages with the first stage being able to drive low input imepedance, typically 600 ohms like the Tango circuit, so a cathode follower is often employed and some purists might argue against it. But who cares... whatever works and whatever sounds good.

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Yes, that's one problem with designing a tube-based LCR; the needed 600-ohm impedance on the input side is hard to achieve with tubes. There are many interesting threads on that subject. One such claimed that you only need 600 ohms on one side of the LCR, not on both input and output side; I am not sure about that. Some use a transformer to achieve the needed impedances. But another approach is to build an LCR that can be driven by a higher impedance, 10K ohms being another more recent standard. A very smart DIY guy I know in Australia has built a high-gain LCR RIAA using ~20K ohm LCR, built from parts supplied by Dave Slagle. I have the schematic. I actually have no idea how or why 600 ohms was ever adopted as a standard or why it is anathema (to some) to deviate from that value. It could merely be that the original LCR modules, made by Silk and/or Tango, in Asia, were set at 600 ohms, and everyone jumped on that bandwagon when those were the only LCR modules available. I welcome input from others who may know more about this.