Palmer Monicon

Design is good. Pretty solid box and nice smooth dial.
Buttons feel a little flimsy.
Stereo imaging is not that great until you turn the dial to 12 o'clock or further.
The mono button creates some phasing issues and does not actually render the signal truly mono. I tested this a number of times - the circuitry is problematic.
The mute button is ok - it causes a slight crackle before muting the signal, so not entirely smooth.
Inputs and outputs are clearly marked, although their orientation is slightly annoying - you end up having to cross your speaker output cables over one another due to the position of the left and right outputs - something I'm always keen to avoid.
Good value for money if you need a cheap and quick controller that's passive and easy to use.