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NFB-9.2
Dedicated Discrete Fully Balanced DAC

Supports full speed Asynchronous Transfer Mode
Built in the Tenor TE8802 chip
Built in 2 Pieces Hi-end grade WM8741 Chips
Price:   USD1330   (Exclude shipping cost)

About ACSS:
     ACSS (Audio-gd Current Signal System) is Audio-gd's system for transmitting audio signals in the current domain. This concept, first seen in 1966, we have used for many years, and since 2005, have evolved the technology to include all audio signals in our systems from the digital source to the power amplifier. Since 2006, ACSS comp5nts have become Audio-gd's most popular products.
　

About NFB-9.2
    NFB means Non-Feedback.
             The NFB-9.2  applies the newest  high-end dual WM8741 which can support up to 24Bit/192KHz input (AES , Coaxial  and USB). Similar to other WM8741 designs, Our NFB-9.2  applies Non-feedback ACSS output stage. The dual WM8741 feed to the ACSS output stage without any OPAs so it can avoid sound coloration .
             The ACSS is a non-feedback technology made with fully discrete amplifiers. Most people know the global feedback design can offer better specs in test measurements, and non-feedback can't do well in test measurements but can offer better sound for the human's ears. Here is a conflict of the classic circuits. But the ACSS opens a new field, it can offer a least coloration sound which is more neutral with very low distortion and high linearity. So it can retain the dynamics, detail and neutral sound but not sound bright or harsh.
            In most design, the WM8741  feed to a difference voltage amp through voltage signal . In NFB-9.2 , the dual WM8741 has feed to the ACSS parts direct through balanced current signal . The current signal mode can  bring the best signal of the DA chips .
            The output buffers are Non-feedback. For low impedance, we applied the dual FET buffer output stage which is quite less colored than most conventional circuits.
            The two OPAs in the NFB-9.2 just for DC serve to keep the output DC offset at zero , allow the DAC analog parts are without couple caps to avoid coloration.
            The 24/192 USB interface outputs a I2S signal to dual WM8741.
            Applied the WM8805 as the SPDIF interface , its sound characteristic is same with the WM8741 which is detail but smooth, and it can support up to 192KHz input.  The WM8805 had quite low jitter (50PS),much less than the CS8416 ( 200PS ).
            Real fully balanced discrete design.
   
      
           
        

         NFB-9.2 applies the excellent dual DA chip WM8741 and excellent analog output stages, but these are not the only keys of the best sound. The power supply is most important. Even applying the best DA chip and the best amp, if matched to a normal power supply, the total sound may still be average or sound musical, but can't be neutral and detailed. That is why it is easy to find hi-end grade gears maybe without the best chips or amp stages, but with plenteous dedicated DC supply circuits.
         Uses three R-core transformers (135W total), one 35W R-core supplies power for digital parts, another two 50W R-cores supplies power for analogy parts. The power transformers and rectifiers are carefully shielded from the electric field of the power transformers and rectifiers' frequency transmission. More than 50,000uf audio grade NOVER capacitors are used to ensure ample and smooth power feed. The NOVER capacitors are specially custom order from NOVER (U.K.) according to Audio GD’s requirement.
         The NFB-9.2 uses total 16 groups PSU .  The 15 groups of high-quality class A parallel connection PSU with dedicated DC supply double-stage PSU, which can offer very clear DC power for the DAC , producing a very black background and neutral sound characteristic. The double-stage PSU is very important for digital parts. Some designs may have very low jitter in theory, but if the power is supplied by a dirty or low-speed power supply, it will increase the jitter and pollute the data, and degrade the sound quality obviously.
         The class A parallel connection PSU has very high input impedance to avoid pulse through the PSU from affecting the DAC and low output impedance with very fast speed and high linearity, so it is a very clean power supply. In my experience, its sound is better than battery power supply, better human sound and neutral .
         To achieve high S/N,  the control circuit is powered with separate regulator.
        The massive  all double stages PSU power supply.  
  

 Uses most Hi-end grade parts
          Uses mostly DALE and Vishay resistors,  WIMA ,EVOX capacitors and a lot SOLEN caps. The electrolyte capacitors are custom ordered from NOVER (a UK brand), and exact-matched transistors. RCA sockets are custom ordered and 24k gold-plated, the power socket is RA 24k gold-plated. Neutrik balance sockets and Canare BNC socket .All transistors are Toshiba and Hitachi.

 If I only use the RCA output, is the NFB-9.2 wasted or not fully utilized?
      The NFB-9.2 is a real balanced output DAC, it has XLR (balanced), RCA (single-ended), and ACSS output. There are 4 ACSS amps in the NFB-9.2 for balanced output, and  balanced input, so even through RCA output, the dual WM8741 DA chips will perform fully.