VK-55 Amplifier

Balanced Audio Technology

The Balanced Audio Technology VK-55 represents the meticulous application of modern design principles to the development of a compact, affordable, yet supremely easy to use vacuum tube power amplifier that sets a new standard for musicality in its class. The result is a unique combination of fully balanced, all-triode design topology, automatic biasing of individual output tubes, and a marvelously simple upgrade path to monoblock operation – all in a chassis that is more compact than any previous BAT tube amplifier design.  Beyond its outstanding musical performance, the VK-55 is eminently affordable as well.

Compact Powerhouse

Many of our customers have asked for a smaller and more affordable tube amplifier that meets BAT’s rigorous design standards, while providing the breath of life to music that is characteristic of the BAT sound.  For those customers, the VK-55 is the answer to their dreams!  Moreover, by using the same high-current dual-triode 6C33C-B tube employed in our flagship REX II Power amplifier, the VK-55 delivers the high-current kick required to drive even difficult low-impedance speaker loads.

55 Watts per channel (Stereo) 110 Watts per channel (Mono)

The VK-55 power amplifier is a high-current all-triode design that offers 55 watts per channel in the stereo version or a robust 110 watts per channel as a mono block.  The 6C33C-B triode output tube used in the VK-55 Power amplifier offers many times the current delivery of the more common 6550 tube used in many traditional tube amplifier designs. High impedance vacuum tubes like the 6550 require far more complicated output transformers than the low impedance 6C33C-B vacuum tube.  Consequently, the VK-55 Power amplifier is quite comfortable driving low impedance loads.  You can simply choose the stereo or monoblock version based upon your choice of speaker and room size. The high-current delivery of the VK-55 Power amplifier will give you the assurance of driving a difficult load with ease.

Intelligent auto-bias

The advanced engineering of the VK-55 power amplifier eliminates the traditional headache associated with most vacuum-tube power amplifiers; the constant need to set and readjust the proper bias of the output tubes.  The VK-55 power amplifier features an intelligent automatic bias design that adjusts for changing line voltage and aging tubes, with each output tube having its own dedicated bias circuit.  For convenience, these individual automatic bias circuits contain LED indicators that show the status of each output tube. The BAT auto-bias circuit also ensures that your VK-55 power amplifier sounds wonderful within the first few minutes of listening.  This is indeed very different from manually biased designs that must be adjusted for their thermally warm set point – and thus sound too cold and clinical before their tubes are fully warmed up.

Intelligent power upgrade

The VK-55 power amplifier is easily upgraded from the stereo version to monoblock configuration.  Unlike competing designs, there is no need for the user to trade their amplifier in to obtain more power.  With the VK-55 power amplifier, the user will simply convert their existing VK-55 to a monoblock, and then order a second VK-55 monoblock to match.  Technically, the stereo to monoblock conversion is accomplished by simply paralleling the inputs and outputs.  This means that “the sound” only gets better as both current delivery and power output go up by a factor of two, and the monoblock noise floor drops appreciably as well.


The VK-55 offers the midrange clarity, power, and dynamics that have made BAT one of the most respected brands in high-end audio. The VK-55 is truly able to present a magical open window to the original performance – and a closer emotional connection to the artistry of music. Visit your BAT audio specialist today.  All you need to do is listen!


Output per channel at 8Ω/4Ω 55W / 55W
Output in Mono Configuration 8Ω/4Ω 110W / 110W
THD at full power 3.0%
Input Impedance - mono version 108 kΩ
Tube Complement 4x 6SN7, 4x6C33C-B
Remote Control No
Dimensions (Inches) 17"W x 8"H x 16"D
Weight 50 Lbs
Conversion to Mono? Factory or Wire Kit
Frequency Response 8Hz to 200kHz
Input Impedance - stereo version 215 kΩ
Gain (Nominal into 8Ω) 25dB (20dB)
Number of Power Cords 1
Power Consumption (Idle/Full Power) 400W/800W
Dimensions (mm) 431W x 203H x 406D