A highend multi talent passive box for dynamic, electrostatic and magnetostatic headphones
Of course VERTO is capable of using a high end transistor output amplifier any type of headphones – dynamic, magnetostatic and electrostatic adapt. More equipment is not required to. Use a speaker cable and connect Verto`s golden speaker terminal to the output terminals on your transistor amp and enjoy your STAX headphone in Mode EST ( right position )


The headphone market is growing. There are exciting new high end models available. But one thing remains unchanged – STAX headphones are still one of the most appealing offers in the high end market. STAX is astrong brand with a long history. And we are convinced also with a bright future. Many audiophiles regard the SR-007 and SR-009 as the best headphones in the world.

So what about the amplifier offerings for STAX headphones? In case of a dynamic or planar headphone you have the choice, new headphone amps are announced every month. For STAX the market is different. You can choose the simple way and just order a STAX headphone amplifier. If you don`t like their sound, you tend to prefer something individual or look for one headphone amplifier driving your collection of STAX and also dynamic models the amount of options is very limited. Based on web research you will find a very few and also very expensive high end especially in the US market – often without distributors for other regions.

But who is offering a heaven`s gate model which is affordable and which can be used also for dynamic models ? This gap is now filled by our new electrostatic STAX box called VERTO – design and produced by AudioValve.


The passive box can be used together with AudioValve RKV II and RKV III tube based headphone amplifiers. There was a simple idea behind the VERTO. Why not use the transformer in step up mode to produce the high voltage for the STAX electrostatic headphones? The RKV models use one transformer per channel (impedancer) to drive low impedance headphones (< 100 Ohm). In the RKV III the transformers are mounted inside the case, for the RKV II the impedancer can be bought as a separate box. RKV II and III are regarded to belong to the best sounding headphone amps regardless of price, see many reviews all over the world.

For a game changing product a simple idea is not enough, you have to find also a proper implementation. There are already promising approaches in the market combining transformers with headphone amps to drive STAX headphones. But RKV and VERTO are now exploiting the full potential of that approach. Inductance and capacitance of the transformer can harm the sound. The Pikatron output transformers we use have only very little stray inductances and capacitances. To avoid distortion we use only a low step up ratio of 1 to 5. But key is the fact that the output impedances of RKV II and III are extremely low, too low to cause any negative effect on the sound.

The VERTO supports the current STAX PRO plug with 580 V DC bias as well as the former bias of 300 V used by older STAX headphones. The higher PRO bias uses a 5 Pin connector, the 300 V DC bias can be identified by a 6 Pin headphone plug at the end of the headphone cable. So the VERTO is suitable for all STAX models.

The VERTO has is connected to the headphone amp with a phone cable and standard plug coming with the VERTO. There is nothing to buy for you in addition to the VERTO. Also the VERTO does not require a separate supply voltage. This ensures that there is no interference and hum caused by main connection. The RKV III has to be switched to the OTL mode when driving the VERTO.

To increase the versatility we implemented a switch for 8 ohm as well as 32 ohm. So you can connect high efficient loudspeakers as well as headphones with low impedance. Feel free to drive mobile headphones designed for Apple devices as well as low impedance high end planars like Audeze or Abyss. Check to drive your high efficient loudspeaker with your tube and transformer based RKV and VERTO chain!

Since the connection of the VERTO to the headphone amp is implemented via a standard phone plug you can use it also with other headphone amps instead of the RKV II and III. You will achieve very good results in the case you use a headphone amp with low output impedance and a high output voltage. We doubt that you will get to the same ultimate sonic quality as with the RKV models. The RKV II and III are able to deliver 100 volts peak-peak drive.

We use only high quality components in the box. The Picatron transformers are built based on our specifications. For wiring the main audio connections to the sockets of the headphones and the STAX female socket cable we use a well-known German high end audio cable manufacturer by the name of HB cable design from Cologne. The core of the cable is made of silver-plated oxygen-free copper conductors stranded several times.


Verto – that universal genius – can handle 6 different mode.
low impedance magnetostatic / dynamic headphones
1) 6.3 mm jack at RKV in mode 1 or 2 on VERTO
2) 6.3 mm jack plug and an adapter cable and connect to any large and small transistor amp ( VERTO mode 1 or 2 )


3) the 6.3 mm jack in RKV and speakers connecting at the speaker terminals of VERTO ( VERTO  mode 1 ) electrostatic headphones ( generation of the bias voltage independently )
4) the 6.3 mm plug to RKV model 2 + 3 ( VERTO mode 3 )
5) the 6.3 mm jack plug in an adapter cable to a large transistor amplifier ( VERTO mode 3 )
6) reverse mode – in to the speaker terminals from VERTO connected by a transistor amp (VERTO mode 3)

Specification: The device provides both required static voltages of 300 / 580 VDC for the operation of all STAX headphone models and up to 550 Vrms signal voltage

VERTO model versions:

VERTO, standard –   690, – EUR
VERTO HB                 990, – EUR      ( highend HB-CABLE DESIGN configurated )


6.3 mm standard adapter cable to connect to  transistor output terminals, length 1,5m – price: 92,- EUR
6.3 mm HB Cable Design highend adapter cable for connection to transistor output terminals, length 1,5m – price: 398.- EUR
1, 5 meter – four wire 1.5mm2 OFC copper speaker wire with 8 bananas for connecting the speaker terminals of a transistor amp to Verto – price: 95,- EUR


– Compatible with all STAX electrostatic headphones (580 V DC PRO bias 5 Pin connector as well as 6 Pin 300 V DC bias)

– Suitable for low and middle impedance dynamic or planar headphones as well as ultra high efficient loudspeakers

– 3 switchable modes for STAX electrostatic mode, 8 ohm and 32 ohm

– One Teflon female jacket for STAX PRO bias 5 Pin and 6 Pin headphones

– Two Combi jackets phone plug and XLR for dynamic and planar headphones

– Loudspeaker terminals to connect spades or bananas

– 60 cm cable with phone plug fixed to the case for connection to the headphone amp (like Audio Valve RKV II and III as well as other headphone amps with low output impedance and high output voltage)

– No separate supply voltage needed, static high voltage is generated by the signal

– One high quality Pikatron output galvanic coupled transformer for each channel

– Internal bias voltage for STAX 300 + 580 VDC (LED controlled)

– Internal HB cable design with a cross section of 0.72 sq. mm, embedded in a PTFE Teflon insulation air. The conclusion is a 5 mm diameter strong silicon of insulation, the high-voltage signal line outwards reliable and well insulated

– The device provides both the required for the operation of the headphone-static voltage of 300 / 580 VDC, and up to 550 Vrms signal voltage

– Bandwidth up to nearly 100 KHz – ( 470 pf load )

– Dimensions:  w * h * d ( cm ) – 110 * 105 * 165

– weight: 2 kg


– Silver case (black on request)

– Chrome mode switch (golden on request)

– Cable with phone plug 60cm length (different length on request)

– Price:  690,- EUR including VAT

How does Verto work?

Verto consists of an impedancer and a bias circuit to generate the DC voltage for the diaphragm of electrostatic headphones. The impedancer is built around a transformer for each channel matching the proper relationship of current and voltage to low impedance headphones.

The bias circuit is needed only for electrostatic headphones. They require a DC bias voltage for their diaphragm – older Stax models require 280V, newer ones 580V. Verto leads the input signal not only to the transformers but also to the bias circuit, starting with a voltage multiplier being able to generate 1,2 kV. Two Zener diodes are used to ensure the two specified DC voltages (300V, 580V). Capacitors are used as storage to ensure a continuous bias independend from the actual level of the input signal. An isolation diode prevents that the stored energy in the capacitor is lost.

How to use Verto?

Immediately after Verto receives an input signal it starts to play. You can immediately listen and enjoy since Verto will sound just from the beginning loud and in very good quality. The best indicator for the existence of the bias is the fact that the connected STAX headphone is playing music. Without bias the Stax would just not work, meaning no noise out of the headphone.

Depending on the input level Verto needs around 2 – 5 minutes to establish the bias absolutely stable and to initially fill the energy storage. So please do no critical listening with STAX headphones during the first minutes. So Verto is very similar to all your other tube and transistor equipment, they need a few minutes to deliver their best performance.

The bias LED at the front panel is a pragmatic tool to visualize whether Verto is loading the high voltage storage for the bias. Please keep in mind that the LED is not indicating the bias voltage itself. There is no need to obey the light. It is only relevant for those who want to know what is going on inside. Depending on the input level after some minutes receiving a signal the LED will light and so indicate that the storage is being filled. After some listening time of around 30 – 60 minutes the light will become darker since the capacitor is getting completely filled, so the charging decreases. The capacitor storage ensures that the bias remains stable for at least 60 minutes after the input signal stopped, since there is no unloading because of the isolation of the storage through a diode.

REVERSE – mode ( gain: + 26,5 dB )

Please connect a transistor amp ( 8 ohms terminals )  with a power output up to 10 > 50 watts to the speaker terminals of VERTO and
turn on the mode switch for “STAX” ( right pos. ). Now you can enjoy VERTO box with your own highend semiconductor amp.Also for headphones enthusiasts wanting to enter for the first time the wonderful world of electrostatic headphones Verto is a high end option enabling you to leverage your existing components – e.g. headphone amps, integrated as well as power amps. So only a small investment is needed.

The little investment should not mislead about what you can expect: driven properly Verto enables you best sonic results for your headphones regardless of price. That is at the end the wondrous and very special story behind Verto.

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