Re: Hughes and kettner valve preamps, tubeman, it it stereo?
Generally, the term "stereo" refers to two independent channels of audio, with different audio information. A single guitar, run into a single pre-amp, run into two power amps/cabinets, is just using two speakers. Its not stereo per se.
The exception to this, would be if you run into something like a stereo chorus pedal, or something that actually creates two different signal chains. Running this into two amps/cabinets would be true stereo.
Or, a guitar with two p'ups, each with their own output jack could be considered true stereo. Its mainly a matter of the two channels carrying slightly different audio information.