The ADA units were flawed in many ways. The power supplies were underpowered meaning the heater supply was below specs for 12AX7, the filtering capacitors were not sufficient, and the OPAMPS were noisy, the list goes on. (Funny todays higher wall voltages actually get you closer to spec voltages since the transformers were 115 v input, and todays wall voltages are 120 and up.
Most guys who have them today get them modded including the preamp to sound more modern.
The EQ section has odd values for Bass, Mids and Treble, which makes it hard to fine tune.
They were cool when they came out but really aren't that great sounding compared to today's offerings.
The ADA's used variable resistance controllers on the cathodes and plates and used grid biasing to voice the preamp. These the MP 1's were designed by Todd Langer.
I have modded many of them for people, and no, we don't need them as a model in the Fractal. There is a reason they are no longer around.
This place
https://www.adadepot.com/ has tones of info, and guys modding and keeping them alive. Most mod them to a state that they don't even sound like the original preamp.