The H&K Tubeman is a floor guitar preamp. It has 3 channels - Clean, Crunch and Lead, all footswitchable with its own dedicated switch.
All 3 channels share the same eq controls and master volume control.

The controls are as follows:
-Clean channel has only a Volume control knob

-Crunch channel has Gain and Volume controls

-Lead Channel has Gain, Voicing and Volume controls

-Eq = low, mid, high

The unit houses one backlit preamp tube (12ax7) which according to H&K injects some non-linearity (analog feel) to the sound.

There is one guitar input unit on the amp and 2 outs - one is a mixer (speaker emulated) output while the other one is for use with a guitar amp.

The unit is housed in a roadworthy metal case that looks like it can take some beating and still perform well.