WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
The consensus seems to be that these amps are VERY price competative but some at the lower end of the price scale use absolute cheap parts...the tube compliment are engineered to use the cheapest type tube available....the designs sometimes are unstable or very lacking in basic Hi-Fi implementation.
Stories of tubes giving out with a few hours of operation have cropped up...The DIY approach is that these amps are a good beginning to modify & upgrade to "esoteric" standards...increasing tonal quality, safety and engineering standards.
__________________________________________Rick (Former Oregonian)
The above poster put it all very well. It's a DIY experience - better to have some knowledge of circuits. There are even some aftermarket retailers that buy the amps and modify them so you can buy a quality controlled product.
But some of the amps sound terrific. A few friends bought the Music Angel 300b amp with 2a3 drivers and 3a5 input. Now that's an all-DHT amp and you just don't get that quality anywhere near the price. With good tubes it's quite superb - obviously decent iron.