First of all the tube amps sold by Tubes4hifi.com amps are a VTA ST-70 and a VTA ST-120 not a "dynakit" ST-70.
The VTA ST-120 has ..
1. A larger power transformer than the VTA ST-70
2. Two larger output transformers than the VTA ST-70
3. Two chokes instead of one as found on the VTA ST-70
4. A larger power supply (more DC storage) than the VTA ST-70
5. A slightly different resistor set on the driver board as compared to the VTA ST-70