Fully-balanced, Class-A preamplifier

The Bach II is a fully-discrete, pure Class A, fully-balanced preamplifier built for systems that need clean switching, precise volume control, and flexible I/O. You get two balanced XLR inputs plus a high-level RCA input, then both XLR and RCA outputs for feeding power amps or active speakers. A 60-step relay attenuator keeps channel balance locked in, plus global voltage power and remote control for daily use.

Balanced connectivity for real-world systems

The Bach II gives you 2 XLR balanced inputs and 1 high-level RCA input, plus outputs on both XLR and RCA. Balanced lines help reject noise over longer cable runs.

Pure Class A, fully discrete signal stage

This is a Class-A, fully-discrete design with a fully-balanced output circuit. Class A means the output devices stay conducting rather than switching on and off, which is one less variable in the signal path. The balanced architecture focuses on low noise and strong channel separation, which is useful when you listen at lower levels and still want space and placement to hold steady.

60-step relay attenuator volume control

The Volume is handled by a microprocessor-controlled relay step attenuator with precision-matched resistors. The benefit here isn’t “more steps” but repeatability and channel matching. Left and right stay aligned as you turn the knob, so the center images stay centered and small level changes don’t skew the stage left or right.

Power filtering that keeps the background quiet

Inside, an 80W toroidal transformer feeds a low-noise linear supply with a capacitor bank and layered filtering using ELNA electrolytic capacitors and WIMA capacitors. In practice, background noise is controlled, so quiet passages don’t get smudged by power-related issues. 

Minimal controls that stay out of your way

Two large knobs handle what you need most: power/source/mute on one side, volume on the other. Laser-engraved labeling is meant to stay readable long-term. The front display keeps status clear at a glance, without adding a row of extra buttons.

Global voltage power input

The power input auto-identifies voltage, with no manual switching (it's built for 100–240VAC, 50/60Hz). If you move between regions or keep a travel rig, it’s one less thing to worry about.

Compact footprint for a desktop or rack

The Bach II is reasonably sized for tight spaces. The chassis measures 13.23 in × 11.97 in × 2.60 in (336 mm × 304 mm × 66 mm), with a net weight of 14.33 lb (6.5 kg).

Product highlights

• Fully balanced architecture with XLR in/out
  
• Pure Class A, fully discrete circuitry
  
• 2 XLR inputs plus 1 high-level RCA input
  
• XLR and RCA outputs for flexible system matching
  
• 60-step microprocessor-controlled relay attenuator
  
• Precision-matched resistors for channel balance
  
• 80W toroidal transformer with layered power filtering
  
• Remote control support
  
• Global voltage power input with automatic identification

Specs

• Type: audio preamplifier
  
• Inputs: 2 × XLR balanced, 1 × RCA high-level
  
• Outputs: 1 × XLR balanced (L/R), 1 × RCA (L/R)
  
• Output voltage: XLR 4.0 Vrms, RCA 2.0 Vrms
  
• AC power requirements: 100–240VAC, 50/60Hz (global voltage)
  
• Power supply voltage identification: ~115V / 230V (intelligent automatic identification)
  
• Whole machine power consumption: 10 W
  
• Standby power: < 1 W
  
• Normal operation: ≤ 25 W
  
• Frequency response: 10Hz–80kHz (+1/−1dB)
  
• Distortion: 0.0005% (1kHz, normal operating conditions)
  
• Signal-to-noise ratio: >110dB (A-weighted)
  
• Channel separation: >105dB (A-weighted)
  
• Stereo crosstalk: −110dB
  
• Dimensions: 13.23 in × 11.97 in × 2.60 in (336 mm × 304 mm × 66 mm)
  
• Packaging dimensions: 20.47 in × 16.34 in × 4.53 in (520 mm × 415 mm × 115 mm)
  
• Net weight: 14.33 lb (6.5 kg)
  
• Gross weight: 21.38 lb (9.7 kg)
  
• Warranty: 12 months

What’s included

• Bach II preamplifier
  
• Remote control
  
• Documentation