From the 2.0 manual-
"The Phi Preamplifier is the world's finest audio preamplifier and an absolutely unique component. Its unusual topology, premium parts, and flexibility make it a pleasure to hear and operate. The line stage is, in effect, a small Class A1 power amplifier, capable of driving loads as low as a few hundred ohms. This is a stark contrast to normal preamplifiers, which claim a low output impedance but completely collapse when asked to deliver current.
The Phi circuit is loafing with a normal load in the 10,000 to 200,000 ohm range, delivering an effortless, musical performance. There is no loop feedback and no coupling capacitors in the line section. All active elements are triode tubes, the purest, most linear amplifying devices yet invented. Output matching is accomplished by way of superb output transformers. As a side benefit, different output grounding configurations are possible, optimizing performance into either balanced or single-ended loads, and allowing ground loops to be broken.
The optional phono stage uses triode tubes operating without loop feedback. Gain is moderately high, with a very low noise floor. Low output MC cartridges are accommodated by means of high quality matching transformers, which contribute voltage gain without noise,
resulting in detail that emerges from a remarkably dark and neutral background.
Remote volume control is implemented via a motorized mechanical device. This provides two major advantages. First, the control is completely intuitive to use. Second, we avoid the sound degradation attendant with VCAs, transistor switches, and switched resistor arrays.
The main chassis is machined from thick aluminum. The separate power supply allows e.m.f. fields, switching transients, and mechanical vibration to be isolated from the audio circuits. The high voltage supply dual choke pi filtering for extremely low noise.
The Phi 2.0 is designed not to the latest fad but to substance, for the highest possible sound quality. Time spent familiarizing yourself with this manual will be well rewarded."