RAAL Requisite

HSA-1b Headphone & Speaker Amp

  • Reference class headphone amp
  • Run ribbon headpohones, normal headpohones and speakers from the one desktop box
  • True balanced design
  • Precision 24-step attenuator for rock-solid left/right balance at all listening levels
  • Pro Audio heritage
  • 5 year local warranty


Simply put, the HSA-1b delivers the most enjoyable, immersive, engaging and outright addictive listening experience I’ve had with the SR1a, short of spending more than double the asking price on high-end speaker amplification!

In fact, I like the HSA-1b so much with the SR1a that I would have had no qualms about buying it just to drive them, even though that wouldn’t be taking full advantage of what it offers. But since I found it similarly compelling with almost every other regular headphone I tried it with, and it reduced my desktop box-count into the bargain, it was an even easier decision - and better value as a result.

Ian Dunmore (@Torq) on Headphones.com



Direct drive amplifier for True-Ribbon Earfield Monitor headphones, speakers, conventional dynamic, and planar magnetic headphones.


  • HSA-1b amp unit
  • Power cable
  • Manual
  • 5 year warranty


  • Delivered <5 business days from purchase
  • Free shipping throughout Australia


Load Impedance: 0.3 Ohm – infinity
Output Power (one chanel driven): 10W /8Ω, 20W/4Ω, 40W/2Ω, 55W/1Ω @ 1khz/sine
Ribbon & Headphones Drive: RAAL-requisite SR-1a, Dynamic & Planar Magnetic
Speaker Drive: 8Ω, 4Ω, & 2Ω Loads
Freq. Response: 100mv/ in/sin. 15hz – 500kHz
Power Bandwidth: 100kHz (-3db) at 1khz
Distortion: < 0,5% at 1khz
Signal to Noise Ratio: Better than 90dB
Input Impedance: 40 kOhm
Sensitivity: 0,5V /40kOhm
Input: IN1- 2 RCA, IN2 – 2 XLR
Max Power Consumption: 150W , without signal 25W
Dimensions: H 90, W 218, D 320mm (3.54 x 8.58 x 12.60 inches)
Weight: 5,3kg (11.68 pounds)