most hardwired valve power amplifiers it is frequently
difficult to get the HT and heater rails properly suspended
and separated, safely and neatly from the chassis, this
especially applies when building amplifiers using the
really high voltage directly heated triodes like 211,
VT4-C, 845, 849, 304TL, DA100 etc.
When planning design like this, it is important to incorporate
suitable layout from the start, and the Denyo stand-offs
should be more or less mandatory in that context.