Reference 80S

Posted 30 July 2023

The Reference 80S stereo amplifier continues Audio Research’s latest design effort in creating a vacuum-tube amplifier that not only redefines ultimate music reproduction, but does it in an incredibly beautiful package.

The 80S was created for the music lover who does not require the output power of its larger siblings, the Reference 160S stereo and 160M mono amplifiers. The 80S continues the design ethos, including dual GhostMeters® that float in front of four KT150 output tubes. Extruded panels, a vital part of the all-aluminum chassis, provide rigidity and beauty.

Outwardly, the 80S shares the same dimensions as the 160M. A single shallow whisper fan is built into the bottom plate. Flexibility is built-in, too, with XLR and SE inputs, 4-8-16 ohm output taps, 12V input and output triggers, RS232 input, tube hour meter, switchable fan speeds, and defeatable auto-off function.

The feature set is the same as the 160S, including a proprietary auto-bias circuit that adjusts for not only tube age, but for powerline voltage swings. There is fusing of the output tubes, single-ended and balanced inputs for flexibility, switchable Triode-Pentode operation to accommodate loudspeakers and personal preference, output tube monitoring, and inclusion of an hour meter so you know how many hours are on the tubes–like an odometer for your amp. This is a tube amplifier that does not require fiddling, it is meant to be enjoyed. The built-in 12V trigger turns the 80S on or off when connected to a modern preamp with a 12V trigger. 

Like every Reference amplifier before it, the 80S is a fully-balanced differential design because it provides the highest performance and lowest distortion. A four-layer circuit board is used to provide a separate ground plane, better circuit layout, and fewer noise-inducing point-to-point connections. Music is projected against a quiet, jet-black background—like looking at the stars out in the country, removed from light pollution. It is magical and enveloping.

Built by hand, from the ground-up in our Maple Grove, Minnesota facility, this is created in service of the music, bringing it to life in every sense of the word. Listening through the 80S is a compelling experience, never a mental exercise. Set up appropriately, the 80S can fool you into feeling you are in the presence of the musical performance: The finest details are heard, with rich harmonics and full dynamic contrasts–from the smallest whisper to the largest crescendo–showcased with the ambience of the original acoustic space. Whatever your reference speakers may be, whether they are from Wilson, Magnepan, Vandersteen, Focal, Sonus faber, B&W, or whatever you like: the Reference 80S will elevate their performance to a new plateau.


Electronic Specifications



70 watts continuous from 20Hz to 20kHz. 1kHz total harmonic distortion typically 1% at 140 watts (33 watts in Triode mode) per channel, below 0.04% at 1 watt (Note that actual power output is dependent upon both line voltage and “condition” i.e.: if power line has high distortion, maximum power will be affected adversely, although from a listening standpoint this is not critical) 


(-3dB points) 7Hz to 68kHz 


(-3dB points at 1 watt) 0.7Hz to 94kHz 


1.4V RMS Balanced for rated output. (25.5 dB gain into 8 ohms); 

0.7V RMS SE for rated output. 


300K ohms Balanced, 75K ohms Single Ended 


Non-inverting. Balanced input pin 2+ (IEC-268) 


16 ohms, 8 ohms, 4 ohms 


Approximately 1.0dB 16 Ohm Load to Open Circuit

(Damping factor approximately 8) 




10 volts/microsecond 


4.0 microseconds 


105-130VAC 60Hz (210-250VAC 50Hz) 420 watts at rated output, 

280 watts in Triode mode, 221 watts at “idle”, 3.6 watts off Units for Japan: 100VAC 50/60Hz 


2 matched pair KT150 (Power output V1-V4); 2 6H30 (Gain stage V5, V6)


Width 18.5” (47 cm) chassis; 19.0” (48.26 cm) faceplate.

Height 10.5” (26 cm) 

Depth 18.5” (47 cm) 

With handles & connectors: 21” (53.3 cm) 


62 lbs. (28.2 kg) Net; 73 lbs. (32.7 kg) Shipping.