ZOTL40 Reference+

About the ZOTL40 Reference+

The Linear Tube Audio ZOTL40 Reference+ amplifier is a flagship tube amplifier that employs David Berning's patented Zero-hysteresis Output TransformerLess (ZOTL) technology. It delivers up to 51 watts per channel into 4 ohms with 0.5% total harmonic distortion, using a push-pull Class AB output stage. The amplifier features a refined chassis and component improvements, including Mullard NOS EL34 tubes known for their excellent midrange and authoritative punch. It has a frequency response of 8Hz to 50kHz, an input impedance of 50k ohms, and an output impedance of 1.6 ohms. The amplifier is auto-biased with no manual adjustments needed. It includes multiple inputs (4 stereo RCA single-ended inputs with Cardas connectors and 1 XLR unbalanced single-ended input), headphone output, and preamplifier outputs. The volume control is a stepped attenuator with 1025 steps and 100 positions for fine resolution. The amplifier weighs 15 lbs and is housed in an aluminum case. It is hand-built in Washington, D.C., and praised for its tonal neutrality, detailed imaging, and musical midrange, making it suitable for long listening sessions without fatigue.