These boxes use dual 3 PDO circuit 8 pin DIL floating mass.
These are high performance AOPS that surpass any preamp market for example.
They 115db minimum dynamic.

UTILIZATION

Very easy to use
BUT:
-Do not store in a damp place or subject to variations in temperature close to 0 °
-No input protection diodes by PDO (a massive problem over 20volts will destroy the PDO concerned).
-Knobs are not provided for resisted moisture also: a rainy climate, even if they are in the shelter, will be right in the long run them.

SOUND QUALITY

-The sound quality is very good: there is one on the top of the keypad.
These boxes do not color the sound: they are neutral.
The followers of a particular brand will be disappointed but hey, they questioned its color anything.

OVERALL OPINION

I have used 2 times but I have to buy to keep this both inside and warm!
Always plugged in all the earth plane before the units can otherwise spend.
For those who want loonnnggguuueees symmetrical connections, these small boxes will do wonders.
Tested successfully on 30 meters.
If they were robust to humidity and power surges, they would be 10/10.