Gruensch power amplifier

Is any of you familiar with Gruensch power amplifiers from Germany? How would you describe the sound of these amplifiers? Which preamp would be a good match for them?
If you could give them a rating (1 to 10*), which rating would you give them? Thank you.
*Regarding musicality, fluidity, treble smoothness, soundstage, bass quality, midrange palpability and presence, detail resolution and dynamics.