basically, the 12AX7 in the hybrid amp is used only in the preamp section as what chimaera said. it only uses a single tube, however the tube may be in various sections in the preamp. tube amps have a tube preamp and power section. the preamp section will consists of various sections all using the tube, (probably 1 tube for each channel, phase inverter tube, reverb tube). The distinct "tube distortion" is produced when the poweramp stage of the amplifier is being pushed, which indirectly means you have to increase your tube amp volume if you want to achieve a "power tube saturation", which indirectly means the police may come knocking on your door to tell u to shut the hell up. :lol: