New: Audalytic HP70 Fully-Balanced Discrete Headphone Amp
Fully-Balanced Flagship Amp
The AUDALYTIC HP70 is a desktop headphone amplifier and preamplifier built around a fully-balanced discrete Class-A architecture. Designed as a central analog control point for both headphone and speaker systems, it combines four pairs of power MOSFETs, an R-2R relay volume control, adjustable gain from 0 to 28dB, and both balanced and single-ended connectivity. With dedicated headphone outputs, preamp functionality, remote control support, and a low-noise internal power supply, the HP70 is intended for users who want a single device to manage multiple audio sources and output destinations.
Fully balanced Class-A amplification
At the core of the HP70 is a fully-balanced discrete Class-A amplifier circuit using four pairs of power MOSFETs. Rather than relying on an integrated amplifier chip, the design uses individual components throughout the amplification stage, allowing the HP70 to control operating parameters at the circuit level. The Class-A topology keeps the output devices conducting continuously, while the balanced signal path maintains separate positive and negative phases through the amplifier.
Relay-controlled volume with four-channel matching
The HP70 uses an R2R relay volume control system instead of a conventional potentiometer. Volume adjustment is handled through a network of precision resistors and relays, providing discrete attenuation steps while maintaining channel consistency across all four signal paths in the balanced circuit.
Accurate channel matching becomes particularly important at lower listening levels, where small tracking errors between channels can become more noticeable. The relay-based implementation is designed to maintain stable left-right balance while providing repeatable volume adjustments throughout the attenuation range.
Integrated preamp functionality
In addition to headphone amplification, the HP70 can operate as a dedicated preamplifier. Users can disable the post-amplification stage and use the unit purely as a signal control component for powered speakers or a separate power amplifier. This allows the HP70 to remain at the center of a desktop audio system while serving multiple listening scenarios.
The preamp section incorporates two socketed LME49720 dual op-amps, giving users access to a well-known audio-grade operational amplifier platform. Switchable preamp outputs make it possible to move between headphone listening and speaker playback without changing system connections.
Power supply and system connectivity
The HP70 includes a built-in 30VA low-noise power supply designed to provide stable operating voltage to the amplifier circuitry. Multiple independent voltage regulation circuits help reduce ripple and electrical interference across different sections of the device. For users who prefer an external power source, the HP70 also supports 15–18V DC input.
Connectivity is designed for desktop systems with multiple sources and outputs. The rear panel includes balanced XLR inputs, two sets of RCA inputs, balanced XLR outputs, and RCA preamp outputs. The front panel provides both a 4.4mm balanced headphone output and a 6.35mm single-ended headphone output, along with touch standby control, a display, and a central control knob for volume and settings adjustment. Remote control support adds convenient operation from a listening position.
