MicroZOTL Level 2

About the MicroZOTL Level 2

The MicroZOTL Preamplifier Level 2 is a Class A tube preamplifier and headphone amplifier using Linear Tube Audio's patented ZOTL (Zero-hysteresis Output Transformer-Less) topology. It is based on the original microZOTL preamp/headamp circuit (1 Wpc into speakers) but incorporates the Level 2 upgrade package focused on higher-grade parts and refinements rather than a change of core architecture. The chassis is the full-width Fern & Roby-designed enclosure, approximately 17" W x 12.4" D x 4.2" H, with a black aluminum casework style shared with the Level 3 preamp. It functions as a line-stage preamplifier, headphone amplifier, and low-power speaker amplifier (via its 1 Wpc ZOTL output stage), and includes multiple stereo RCA inputs plus an additional balanced XLR input that is transformer-coupled using Lundahl transformers. Core circuit characteristics include push-pull Class A, no global feedback, about 1 W into 4 ohms / 0.5 W into 8 ohms, 0.6 V sensitivity, 2 ohm headphone output impedance, and approximately 50 ohm preamp output impedance. It uses a ceramic main circuit board with 2 oz copper traces to reduce parasitic capacitance and dielectric losses, improving transparency and presence. The Level 2 upgrade focuses on the signal-path capacitors and power supply: the preamp output capacitor is upgraded to a premium Clarity CMR capacitor (with headphone and preamp outputs separated and optimized independently), and stock power-supply and storage capacitors on the audio board are replaced by Mundorf Mlytic AG capacitors, increasing total power-supply storage by about 22,000µF. Control and usability improvements include remote-controllable volume, input selection, and channel balance, a digitally controlled analog volume system with 100 steps and a "Hi-Res" mode with up to 199 steps for finer adjustment, and per-channel gain options of 0 dB, -15 dB, and -30 dB. The tube complement is 2x 12AT7 input/phase-splitter tubes and 2x 6SN7 (or compatible 12SN7) output tubes, with a switch on the ceramic board to select between them. Overall, the MicroZOTL Preamplifier Level 2 is a reference-grade, full-function tube line stage and headphone amplifier for demanding audiophile systems, praised for its very low noise floor, strong dynamics, and high transparency.