Discrete Class A headphone amp and preamp

The AUDALYTIC HP70 is a desktop headphone amplifier built around a fully-balanced discrete Class-A design, four pairs of power MOSFETs, R2R relay volume control, and flexible preamp operation. With 4.4mm balanced and 6.35mm single-ended headphone outputs, XLR and RCA inputs, XLR and RCA preamp outputs, adjustable gain, and remote control support, it gives headphone listeners and desktop speaker users a serious analog control center without turning your desk into a mess. 

Class-A amplification with discrete control

The HP70 uses a fully-balanced discrete Class-A amplifier circuit with four pairs of power MOSFETs for tons of driving power for demanding headphones. A discrete design uses individual circuit components instead of relying on a single integrated amplifier chip.

Balanced performance from more than balanced inputs

The HP70’s input stage uses a fully-balanced topology, with single-ended to balanced conversion for RCA sources. That means you can connect a standard RCA source and still benefit from the amplifier’s balanced internal signal path. 

Relay volume control for four-channel precision

The R-2R relay volume system provides precise level adjustment while maintaining consistent channel matching across all four paths. This matters most at lower listening levels, where small left-right imbalances can become noticeable. Instead of relying on a basic analog pot, the HP70 uses a relay-based approach designed for cleaner, more stable volume steps.

Preamp mode for speakers and headphones

The HP70 can work as a dedicated pure preamplifier by disabling the post-amplification stage. It includes two socketed LME49720 dual op-amps in the preamp section and switchable preamp output for moving between headphone and speaker use. Keep it at the center of a desk system, then send signal to powered speakers or a power amp when you're not using headphones.

Power supply designed to keep noise down

A built-in 30VA low-noise power supply gives the HP70 stable internal power, while support for external 15–18V DC input adds another option for users who want to pair it with a separate supply. Multiple independent voltage regulation circuits help reduce ripple noise and interference, keeping the amplifier section focused on the audio signal rather than electrical clutter.

Front-panel control without the clutter

The front panel keeps daily use simple with touch standby, a display, a central volume and setting knob, a 4.4mm balanced headphone output, and a 6.35mm single-ended headphone output.

Rear-panel connections for a full desktop system

The HP70 includes balanced XLR left and right inputs, two sets of single-ended RCA inputs, single-ended RCA outputs, balanced XLR outputs, DC 15–18V input, power input, and fuse access.

Product highlights

• Fully balanced discrete Class A headphone amplifier
  
• Four pairs of power MOSFETs for strong headphone drive
  
• R2R relay volume control with 4-channel matching
  
• Single-ended to balanced conversion for RCA inputs
  
• Pure preamp operation with post-amplification disable option
  
• Two socketed LME49720 dual op-amps in the preamp stage
  
• Built-in 30VA low-noise power supply
  
• External 15–18V DC input support
  
• Multiple independent voltage regulation circuits
  
• Adjustable gain from 0 to 28dB
  
• Remote control support
  
• 4.4mm balanced and 6.35mm single-ended headphone outputs
  
• Three line inputs and two preamp outputs

Specs

• Product type: Fully balanced discrete headphone amplifier
  
• Amplifier design: Fully balanced discrete Class A
  
• Power devices: 4 pairs of power MOSFETs
  
• Preamp op-amps: Dual socketed LME49720
  
• Volume control: R-2R relay volume control
  
• Gain adjustment: 0 to 28dB
  
• Headphone outputs: 4.4mm balanced, 6.35mm single-ended
  
• Inputs: Balanced XLR left and right, single-ended RCA L1/R1, single-ended RCA L2/R2
  
• Preamp outputs: Balanced XLR left and right, single-ended RCA left and right
  
• Power supply: Built-in 30VA low-noise power supply
  
• External DC input: 15–18V DC
  
• Dimensions: 8.66 in. × 6.69 in. × 1.97 in. (220mm × 170mm × 50mm)
  
• Remote control: Supported

What’s included

• AUDALYTIC HP70 fully balanced discrete headphone amplifier