The Sappho builds on the foundation of the Dolos but pushes the limits of what's possible in this amplifier form factor with iron of this size.  While the Dolos aims for simplicity and tube rolling fun, the Sappho focuses on electrical performance and efficiency at the cost (literally) of complexity.  

The Sappho features both a softly-started and choke filtered high voltage power supply using a 6CG3 damper diode as well as a negative voltage rail.  This permits the grid of the 211 to be biased very close to 0V and still be driven both above and below that bias point without compromise.  A forward facing 0D3 is retained to help protect the EL34 in the second stage, and bias is made adjustable via a small knob mounted next to the 211.  Rather than a simple linear DC filament supply, the Sappho uses a standalone module that is regulated and which operates outside of the typical frequencies reproduced by a transformer coupled SET amplifier.  To round off the tube lineup, an EF184 pentode is used in the first stage.

The Sappho uses power and output transformers made in the USA, long life Japanese power supply caps, a polypropylene final power supply cap for the high voltage supply, and Russian military paper in oil coupling capacitors.   

Power (Sylvania 211):

29W 3% THD 1kHz

35W 5% THD 1kHz

43W 10% THD 1kHz

Peak Power: 58W

Output Impedance: 1.23 Ohms on the 8 Ohm Tap

Bandwidth:  -3dB at 7Hz and 33.7kHz

Gain: 15dB 8 Ohm configuration

Noise:  Less than 2mV on the 8 Ohm tap