Availability: In stock


ZERO 637U 24Bit / 192KHz USB Decoder + Headphone Amplifier

1 Review(s)
  • Zero 637U with USB function
  • The sound effect is greately improved
  • Improved the power section to eliminate static disturbance
  • Readjust and refine the analogy circuit to improve its function 


Recevial chip CS8416 
Decode Chip AD1852 
Analogy Opamp chip: OPA637 
S/N ratio 105dB 
Distortion 0.0005% 
dynamic range: 117dB 
Frequency Response 20Hz-30KHz 
analogy output frequency: 2V 
Imput port: one digital optical fibre imput 
one digital coaxial imput 
Output port: one RCA analogy un-balance output 
one 6.3mm headphone signal output 
power imput voltage: 110V/220V
Net weight:3kg


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Harald Striepe
Jun 13, 2013 1:01:01 PM
I bought this based on enthusiasts reviews of the ZERO OPA2604U With USB Soundcard Decoder Headphone amplifier AMP 24/192KHZ DAC USB Black, which is identical in design, but features a different Op Amp. Another group of enthusiasts thought the OPA637 sounded decidedly better than its OPA2604, so I went for this version. I have not been disappointed.

I am using this being fed via optical link from an Airport Express, since most of my music is in iTunes. For listening, I either use a Denon head set, or my Even 20/20bas studio monitors connected via ART CLEANBoxPro. This is a minimum configuration with as few electronics in the loop as possible, while being within my budget.

I have not been disappointed. The sound is transparent and well defined, while not having any edgy artifacts. It sounds great with both modern rock and pop, electronic music, and classical. Voices are natural, as string instruments.

Could not be happier, although I am waiting for my Event Opals to come in to upgrade the 20/20bas. After having these, I want more!