I have noticed that more than a few DAC/preamp manufacturers are making claims that discrete DAC/preamp stage (after the DAC chip itself) is sounding significantly better comparing when made with OPAs. Specs don't really justify this thesis but they are still very good, so I find it really hard to believe that it makes any difference in sound. What do you guys think?
Example from Audio-GD:
http://www.audio-gd.com/Pro/dac/NFB1.38/NFB1.38EN.htm
Simple and short signal transfer is best:
The NFB-1 applies the newest ESS high-end Sabre32 DA chip ES9038Pro which can support up to 32Bit/384KHz input .
ES9038Pro in voltage output model , there is -12DB THD+N worst , to be achieve the best performance of ES9038Pro , must work in current output model .
In some other ES9038Pro built in DAC design , ES9038Pro output signal have to through 3 step OPAs implement analogy signal process .
The NFB-1 had different design , applies Non-feedback ACSS design. The ES9038Pro feed to the ACSS circuit by balanced model without any OPAs .
The ACSS circuit naturally working in current model and have design difference current input , it can transfer the ES9038Pro current signal to output and implement the I/V conversion in current model in one ACSS amp . And this ACSS amp only have one current gain stage , the ES9038Pro output signal only through one stage can arrive the output stages .
The shortest signal journey can reproduce the best detail and dynamic, and almost without sound coloration , It can show the real performance of the ES9038Pro .
So our ACSS design is the best combo with ES9038Pro achieve the best performance .
Example from L.K.S. Audio MH-DA004:
https://www.shenzhenaudio.com/l-k-s...bu-for-dop-usb-i2s-optical-audio-decoder.html
4. L.K.S Audio three years ago to proceed with the development of discrete circuits used to replace the traditional op amp chip, because the traditional op amp chip is subject to the chip size and SOC integrated circuit of some innate factors, the composition of the internal circuit of the monomer parts Performance is very limited, can withstand the heat power is very low, basically all of the integrated operational amplifier chip quiescent current is in a very low state (less than 10mA), even if the enthusiast of the senior opa627 gold seal version is the case, Processing ES9018 / 28/38 more and more audio output current (ES9018 / 28 in the mono mode output current is about 30mA or more, while the ES9038 is more than 100mA), so the overall quality of performance can not meet the demanding needs of enthusiasts The The output of the sub-output circuit, the use of twin JFET field effect transistor input, the last pole 3A power tube output, you can easily meet the ES9038pro high current output processing, and after three years of accumulated over 100 circuit parameters tuning, sound Performance is extremely natural, Chiang Kai-shek, high and low frequency of the ductility is excellent.
5. With a high standard of analog output circuit, In order to meet the best performance of this circuit, in particular the design of the same high-grade A (A) power circuit, constant current source SHUNT circuit mode design, ON Semiconductor high power Adjust the tube, and use Jensen new electrolysis, with the appropriate output capacitor and decoupling capacitor, natural sound, transparent, very balanced and very musical appeal.