Seeing pictures on the 'Net of what's inside a 1966 Marshall 'Plexi' (J Hendrix's old amp 7206) re: components and wiring made me think as a layman how simple it all looks.
I guess economics, fashion and people's requirements have impacted on amplifier designs in the years after as effects loops, reverb, other additions to amplifiers demanded by users etc. have perhaps ruined the purity of the original guitar amp design? This has also been noted above I guess and is reflected in Wienbrock's design philosophy and approach, i.e not to get in the way of what an electric guitar can produce through quality design, componentry and manufacture?
The classic amps of yesteryear (which were used to define rock music) are indeed relatively simple; however this does not mean it is easy to understand exactly how they work, as very subtle changes can have dramatic effects on the outcome. Clearly the less components in an amp, the more critical each one can be.
Attention to detail is paramount in getting good results with this style of amp. To back up what James has said, I've only had my hands on one Wienbrock amp, but I was very impressed with the build quality, attention to detail and tone.
Smaller builder can have more selective appeal, but a big manufacturer's products have to have wider appeal as they have shift more units simply to stay in business, and so have to include features like fx loops etc as that's what people want.
Having said this, I'm still surprised how many poor sounding amps (at least top my ears) there are on the market.
