THD Flexi 50 Rack-mounted Guitar Amp Head Green
The THD Flexi-50 Rack-mounted Guitar Amp Head is a precision hand-built 50-watt Class-AB amplifier with foot-switchable overdrive/boost, foot-switchable master volume control and the ability to use almost any preamp and power tubes in any combination

THD BiValve Rack-mounted Guitar Amp Head Black
Like the UniValve, the THD BiValve Rack-mounted Guitar Amp Head is a single-ended pure Class A design. However, it has two output valves that are wired in parallel and combined through a special output transformer to deliver up to around 30 watts. You can use almost any output valve you like without touching any kind of bias adjustment, and get this: in the BiValve you can use them in any combination as well. Combined with the capability to take almost any preamp valve, this makes the BiValve even more of an amp-tweaker's dream than its predecessor.