NAT Audio Single HPS

This is an incredible integrated that has some slight scratches(mostly on the power supply) and has been well maintained otherwise. I bought it slightly used and only put a couple hundred hours on it. This integrated comes in a custom Pelican case. I love the sound of this integrated, but I purchased a Constellation Argo and I no longer have a need for it. My loss is your gain on this wonderful integrated. Here is an excerpt from NAT Audio's website regarding this integrated:

Single HPS operates in single-ended, zero global feedback, pure class A manner. Power output is set to 50W into 8 ohms. Best quality of amplification will be with moderate sensitivity loudspeaker with stable impedance from 4 ohms to 16 ohms.

Driver stage in Single HPS form E88CC (or equivalent) tube, capable to act as low distortion stage, made by military standard, indicate as N.O.S. (new old stock) grade of the highest quality.

Output stage form military grade direct heated triode (D.H.T.) GM70, high performance tube capable to dissipate up to 125W. Single HPS represent a truly single-ended design without parallel connection of  tubes with high 50W of power output.

Hand coiled and assembled wide bandwidth output transformer (custom designed for NAT ) is used.

Single HP's bandwidth from 10Hz – 60.000Hz has exceptional good flatness for single-ended zero feedback type.

By specific connection of the output transformer with power tube, amplifier may drive almost any type of loudspeaker with damping factor that is few times higher than normal.

Filament soft start  improve reliability of entire integrated amplifier by avoiding voltage stress during turn-on procedure. Standby function additionally improve reliability of non analog section.

No any adjustment from time to time of output tubes is necessary. Single HPS has automatically adjust current capability for GM70 tube no matter of tube duration – constant current in time domain –  from the brand new to the end point of tube lifespan.

To avoid unnecessary heat Single HPS has possibility to be selected to low mode - 30W of output power with significantly reducing of power consumption!

Power supply section participate in sound quality almost as amplifiers main circuit. Silent power unit of 400W is designed for double power than Single HPS consume.

Over 500J of energy storage is used in form of high quality multi-capacitors bank!

Separate power supply (conditioner) unit additionally improve sound quality by removing magnetic leakage flux inside the main chassis!

For the highest "purity" of power supply voltage a special designed and selected passive components are used. Tonal quality is totally independent from line voltage instability. 

Attenuation network as one of the most important part of any integrated amplifier is realized in Single HPS as 56 high reliability silver contact silent relays network. Only one resistor of high quality at any volume setting is on the signal path (shunt type) ! Volume control linearity is at high level - from DC to over 1MHz!

Single HPS is equipped with multi function remote control unit made from solid block of aluminium. Front panel is made from solid block of aluminium as well! Indication of all amplifiers function is shown by blue led's on universal function display.

Quality of electronic components that is used inside Single HPS are at high level - military grade and N.O.S. tubes, Teflon and "in-oil" military grade capacitors, Caddock and Vishay 5ppm resistor, Ohmite Alumina HV type resistor, many electrolytic capacitors for 105C of operating temperature, last generation J-FET semiconductors, laboratory grade speaker connectors, Hammond mechanics, teflon isolated silver-ofc military grade wiring…