Technical specs:

Transmission ratio  1:1
Input resistance – not less than 4mOhm
Output resistance – not more than 10 Ohm
Harmonics coefficient – (0 dBu, U — 12В) not more than, – 0,002%
Overload ability (Harmonics coefficient less then 1%)
With 12V power – not less then +12dBu
With  9V power – not less then +8dBu