The multi award winning Reference linestage continues to get better.  We have now paired our amazing 300B input stage with the award winning Reference linestage. 

The Purity Master Reference is a Class A linestage fitted with a 300B front end based on our unique Harmonia DHT input circuit and is the result of years of intensive research directed at attaining the most accurate reproduction of recorded music.  Unique topology and application of the most advanced technological resources and processes bring the Purity Master Reference to a threshold of excellence in sound reproduction.  To add to the main features, the Master Reference now contains 4 completely isolated power supplies. We are using a dedicated power supply for each of the two tube stages as well as for the filaments and remote system

The balanced version of the Master Reference utilizes transformer coupling at both the input and output. Transformer coupling output results in a low output impedance making the Purity Reference a versatile unit that is capable of driving both solid state and vacuum tube amplifiers with input impedances as low as 600 ohms. Extraordinary transparency of perceived sound which in turn assures the recreation of a three dimensional soundstage.

The Master Reference now incorporates the ultra clean SonicCap capacitors in both the 300B input stage as well as the 6SN7 output stage. Enhancements in the power supply include the use of high current toroidal transformers (4 pieces) and JJ Electronics power supply filter capacitors. Tube filament power is now supplied by a high quality, highly regulated DC supply for the quietest possible presentation.

The Master Reference features a very short clean signal path and the same small 1db step size as the optional autoformer system  - giving a range from -60db up to unity gain.


We have taken our Harmonia 300B tube stage and utilized it as the input stage for the Master Reference. Input signal is fed directly into the grids of the 300B tubes. The output of this stage is then fed to the Bent Audio volume control system using the resistor//relay based volume control modules. The volume control then routes the signal to our Reference 6SN7 circuit. 

Balanced Version

With 3 sets of balanced inputs, 3 sets of unbalanced inputs and 2 sets each balanced and unbalanced outputs, connection possibilities are vast. When an unbalanced input is selected, the signal still passes through the input transformer maintaining a low output impedance as well as the resolution and transparency transformer coupling is known for.  Single ended outputs also benefit from transformer coupling. Absolute phase and balance control are selected both through the supplied aluminum remote handset and the front panel controls.

As with all Purity Series products, the remote circuit has been granted a dedicated power supply including a separate, standalone power transformer as not to interfere at all with the analog circuit.


- 0 dB negative feedback
- Pure tube design (no transistors)
- Autoformer attenuation/volume control (optional)
- DynamiCap capacitors
- Shortest possible signal paths
- Very low output impedance to drive any tube or solid state power amp
- Audiophile grade passive components used in all applications
- Teflon tube sockets
- Central one-point earth grounding
- Fully hand assembled to insure the highest level of craftsmanship 
- Relay based source selector with no shared grounds
- No common ground between any inputs.
- 100% point to point wired - NO PCB
- ROHS silver solder used for the best electrical connection
- Selector switch engages relays located near RCA jacks to switch all inputs

- 2 300B input buffer tubes
- 2 6SN7 or 12AU7 tubes for stereo line-amplification
- Regulated DC filament supply for signal tubes
- Balanced output transformers (balance version)
- Balanced input transformers  (balance version)
- Premium internal signal cable 
- Twin chamber design separated by aluminum plate effectively fights against RFI and EMI.
- 3 pair XLR balanced inputs
- 3 pair RCA single ended inputs (transformer coupled)
- 2 sets XLR balanced outputs
- 2 sets RCA single ended outputs (transformer coupled)
- All 4 sets of outputs active at all times allowing for multiple configurations for bi-amping or use of an active subwoofer(s)
- RCA high quality Teflon silver input jacks
- Neutrik/Swiss - XLR chassis connectors
- Remote Control for Volume, Balance, Mute, Phase Reverse & display off
- Chassis material: Aluminum
- Chassis finish: Black anodize
- Solid aluminum remote handset
- Equipped with high quality IEC AC power cord
- Made in USA
- Three years parts and labor warranty. 90 days on supplied tubes

ONLY ONE AVAILABLE - We are offering only one Master Reference preamplifier in this chassis, under the Purity Audio Design umbrella.

Please contact us for full details and turnaround time.

Selling Price - $14,995 single ended

                        $15,995 balanced

NOTE: Our DHT input stage is NOT a cathode follower buffer stage. Our DHT input stage utilizes the full sonic potential of the DHT in use.


300B Buffer input stage

Class "A", Zero feedback, 6SN7 output stage
Circuit gain: adjustable from 15dB 
Input impedance: 100K Ω
Output impedance: 600 single ended <180 Ω balanced
Recommended output load: >2000 ohms
Frequency response: 13Hz-35kHz -1dB
AC Power Requirements : 117/220/230/240 volts (factory wired)
Fuse: 2A amp fast blow (1/4" x 1-1/4")
Tube lineup : 2x 300B - 2x 6SN7 or 12AU7
Dimensions : 16" Wide x 16" Deep x 6" High
Net Weight :

Power Supplies

300B Input Stage

- High current toroidal transformer

- Choke filtered power supply 

- JJ Electronics filter capacitors

- Plate choke on each 300B

- Pete Millette filament supplies. one for each tube.

6SN7 Line Output Stage

- High Current toroidal transformer

- Choke filtered power supply

- JJ Electronics filter capacitors

- DC Regulated filament supplies
  (one per tube)

Dedicated power supply for remote system

300B tubes will protrude thruugh
​the top panel approxamitely 2"-3"

Purity Audio Design

Master Reference

300B/6SN7 Preamplifier