With regards to the CAT preamp being able to play low output mc cartridges, let me say this about that. I honestly don’t think that you can play any mc cartridge with an output below .47mV without a lot of noise. If you say otherwise, you have a high tolerance for noise.
And let’s expand that beyond just the CAT. Any pure tube phono section simply can’t amplify low output mc cartridges without adding noise. People with minimal to no understanding of electronics simply don’t understand how low of a voltage that low output mc cartridges represent to the input of a pre-preamp or a regular phono stage. There are lots of cartridges that hover around the .2mV range and some that even dip into the .1mV range. By comparison, the average mm/mi cartridge has an output of around 4.7mV which is a huge difference.
Tubes have a noise floor which is higher than transistors and can’t be denied. As tubes age, it’s common that they become noisier. When you are trying to amplify a signal that is .23mV for example, you are amplifying a signal that represents .00023 V. No matter how you cut the mustard, you are into the noise floor of the tubes. If you love the sound of low output mc cartridges and you don’t want the signal riding on a bunch of noise, you are forced to go SS or use a trafo. I prefer to use a SS phono section and keep the noise out. Anyone want to buy a Counterpoint SA-2 pre-preamp??
Understand what you're saying about noise, but not so sure about that. One thing that one also must consider is the amount of gain in your line stage. Many line stages, because of digital, now are only about ten to fifteen dB; CJ tends to be the exception with almost 25 dB of gain in their line stage. So you can have 53 dB in the cj phono and 25 dB in the line and if you have a sensitive amp (say 0.75 mV instead of my ART's 1.8 mV ), one can use about .3 mV (also some cartridges like the Benz, sound like they have more output than they are rated--and it's not due to the way the output is measured).
That said, I'm finding I want the gain in the phono as long as of course, it doesn't overload the line stage. With the GAT, I find around 60 to 62 dB optimal now (with the insensitive ART amp)
Two, the phono sound best with the gain in the phono eg. if we're talking a total of 80 dB, 60 in the phono and 20 in the line or even 65/25.
Next, there are some "pure" phono stages such as the Doshi and TW Acoustics that have 60+ dB and sound darn quiet. The question, though as always, is for how long will the phono stage sound quiet. And you know that not just any tube will do; one has to carefully select for these low noise tubes.
Lastly, I'm using the Allnic phono with a very unique SUT that gives me the best of both worlds. And it wasn't until the Allnic that I liked the sound of a SUT!