Very sturdy and well made power soak 200 W! It has impedance selector, 2 controls to the power attenuation. The other cuts to 0 dB, - 3 dB and -5 dB. The other works with the "variable" setting. I used mostly only that setting.
In the back there are very well documented "output to speaker" and "input to amp" places so you cannot connect it wrong...
I used this with couple of amps and to my mind it didn?t affect the sound too much. The price may be quite high but it is a quality product and if you want to attenuate/cut the power from your tube amp it is worth it.