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Welcome to Decware



Single-Ended Triode Gain Stage

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The ZSTAGE is basically a single tube preamp with a single pair of inputs and a volume control.

It's typical use is as a gain stage on the output of a DAC or Phono Stage to give it more kick and a more tube like sound.  That is to say that it becomes part of your source component.   It has been designed with lower voltages so that it can stay on 24/7/365 without prematurely wearing out the tube.  You basically just set it and forget it.

The exception to the above would be for those who want to use it as a purist single tube preamp.  In that case it still remains on 24/7 (there is no power switch) so that it is always warmed up and in its peak sound quality zone, but you would use level control as your volume control.  A typical example is DAC connected to ZSTAGE connected to POWERAMP.


The ZSTAGE is built around the popular 12AU7 dual triode and operates without negative feedback.  There is a bias switch located on the front that allows you to have two gain settings, low gain and high gain.   The tube is located on the front of the ZSTAGE for ease of access.  Tube life in this product is typically many years due to the reduced voltages.


You can have yours built with your choice of standard audiophile volume control or 20 position stepped attenuator.  The standard control is made from a warmer sounding carbon, while the attenuator is made from low noise SMR with gold contacts and is more neutral sounding.  20 positions is barely usable as a volume control because the steps are somewhat large, however it does work well as a level control for those set it and forget it applications. 

Also we have your choice of either film or foil capacitors for the signal path, foil being slightly better in dynamics.

Also there is a tube regulation option that uses a special hard wired VR tube on the inside of the unit.  This tube does not typically ever wear out or have to be changed.  It is used in series with the tube to filter the incoming power for better liquidity in the sound.

These options can be configured in the shopping cart.


The size of a ZSTAGE is 10 x 6 x 2 inches excluding jacks and knobs. The case is made from steel with a black textured powder coat finish. There is no heat, so side and top clearances are a non-issue. 

  • Power consumption - 4.5 watts.  Available in 100~120V or 220~240V 50/60Hz.

  • Input Impedance - 100kOhms

  • Max Input Signal - 2 volts

  • Max Output Signal - 7 volts

  • Gain - up to 11dB into 100kOhms and up to 8dB into 10kOhms

  • THD Low Gain setting with 1 volt input at max volume - 0.3% / 2 volt input - 1.4%

  • THD High Gain setting with 1 volt input at max volume - 1.4% / 2 volt input - 5.1%

  • Unity gain setting average with 1 volt is 0.3%, at 2 volts is 1.2%.  

  • Max Noise and Hum - 60dBU.  At unity gain -70dBu.

  • Net Weight - 4.5 lbs

  • Includes power cord with fused IEC connector.

Comes with your choice of knobs


Knob types: Ebony, Gold, Black chicken head, Cream chicken head, Rosewood

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This product is hand built in the USA by DECWARE / High Fidelity Engineering Co. It comes with a lifetime warranty to the original owner. If you purchase one second hand and ever have questions or technical problems we are happy to check it out for you and service it if needed for a very reasonable rate.

We have never sold this item as kit but that doesn't mean you won't find someone else's work inside if you buy one used.  If this is the case and the work and parts are anything less than what we would do, it will be removed and the ZSTAGE returned to its like new condition at the present owners expense.



Made by hand in the USA and sold wholesale to the public with a 
L i f e t i m e   W a r r a n t y  !

No product

ZSTAGES are hand-built to order.  There are presently lots of orders on our real time build sheet.   A 10% deposit secures your place on the list with today's date and time stamp.  Balance is due when it's ready to ship. You will be sent a final invoice with the total price including actual shipping costs by our office during your wait.  NOTE: This item is built on our accelerated build sheet that has shorter wait times.

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