Little Dot MK III tube headphone amplifier 350 mW 300 ohm

Little Dot MK III tube headphone amplifier

The Little Dot MK III is a tube headphone amplifier built around a single-ended push-pull OTL Class-A circuit. It uses GE 5654 and 6H6PI tubes to deliver a neutral tonal balance with precise imaging. The design targets listeners who want high-voltage tube drive for high-impedance headphones without the coloration of transformer-coupled designs. It is not suited for users who need balanced XLR inputs or integrated DAC functionality.

Variable gain and impedance range for system

The amplifier offers four selectable gain settings at 3, 4, 5, or 10x to match source output levels. Input impedance is 50K ohms, presenting an easy load to any line-level source. Recommended headphone load spans 32 to 600 ohms, so it pairs with both portable and high-impedance models. The OTL topology frees the signal path from output transformers, preserving transient speed.

350 mW into 300 ohms with clean headroom

Rated output reaches 350 mW at 300 and 600 ohms, 300 mW at 120 ohms, and 100 mW at 32 ohms. THD+N measures 0.15 percent at 80 mW into 300 ohms, confirming low distortion at typical listening levels. Frequency response extends from 12 Hz to 100 kHz within -1 dB. Power consumption is 30 W from a 228 V supply drawing 0.130 A. It cannot drive planar-magnetic loads that demand several watts.