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Linear Tube Audio and David Berning have produced the ZOTL40 Mk. II. A worthy flagship and the most refined manifestation of Berning's ZOTL design. The ZOTL40 Mk. II Power Amplifier provides 40+ watts per channel with accurate, uncolored sound and automatically protected circuitry.


The Mk. II version incorporates KT77 tubes and a few other component changes to make this great amp even better. These products are based on Berning's patented architecture known as ZOTL, which stands for ZERO Hysteresis Output Transformer-Less.



H - 8.5", W - 9", L - 14.5" (including binding posts)

Audioism40 Headphone Amplifier

  • • Sensitivity: 1.2V RMS for 40 watts output
    • Output impedance 1.6 ohms
    • Input impedance: 50k
    • 100V / 120V / 240V operation: Auto-switching
    • Hum and noise: 94dB below full output (measured between 20Hz-20kHz) • Power output with 4-ohm load: up to 51W, 0.5% THD
    • Power output with 8-ohm load: up to 46W, 0.5% THD
    • Frequency response (8-ohm load): 8Hz to 50kHz, +0, -.5dB
    • Amplifier class: Push-pull Class AB
    • Net weight: 9.7 lbs. or 4.4 kg
    • Finish: Aluminum case
    • Tube complement: two 12AX7s, two 12AU7s, and four KT77s

    • Designed by David Berning
    • Hand-wound coils & impedance converters
    • 40 watts per channel with little or no hum
    • Frequency response flat from 8Hz to almost 50Khz
    • Transformer-less design eliminates intermodulation distortion inherent in all transformer designs
    • Impedance converters effectively produce theoretically ideal output transformer turns ratio
    • Low impedance output easily matches a wide range of speakers and cannot be damaged with no load
    • No adjustments – tubes are auto-biased
    • Automatic protection circuitry
    • High voltage turn on delay to maximize tube life
    • 10 - 20 years tube life depending on use
    • Push-pull, Class AB output stage
    • No heavy power or audio transformers
    • Berning-designed, custom universal voltage power supply (autosensing 100-240VAC 50/60Hz)
    • Has one input through Alps volume control
    • Second set of inputs bypass volume control for direct input
    • Uses 4 KT77s, 2 12AU7s, 2 12AX7s
    • One year warranty including tubes (international buyers pay shipping
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