Seriously, those 'preamps' are hardly anything more than obscure products. Their sales would be insignificant and their installed base, even less significant. They are not, nor ever will be mainstream HiFi preamplifiers. Probably sold 10 thousand between all of them.
Let's get real. The standard input sensitivity for domestic HiFi power amplifiers has been 1.0-2.0V for 50 years. Even with balanced, you can double that on a bad day. So 2.0-4.0V. Anything else it utterly stupid.
Yes, I have preamps that will output 30V RMS, but they are outliers and their rated output is 1.5V.
12dB is a joke. Nobody takes that seriously. Power amplifiers are ~26-29dB. Even Amir tweaks his integrated levels to be somewhere near that.