Different between NFB-28.38 and NFB-28.28: The difference is that NFB28.38 has built in ES9038 Pro, NFB28.28 has built in ES9028 pro, other parts are exact the same. As for sound quality, NFB28.38 has slightly better sound transparency. Differences with NFB-29.38: The NFB-29 is a single ended DAC with headamp and preamp (+/- 30V DC high voltage power supply ), The NFB-28 is balance DAC with headamp and preamp (+/-15V DC power supply ). So They had same output power specs and can drive most headphone very well. If customer has headphones with single ended connector (6.3MM), choice would NFB-29 you will get better performance than the NFB-28. If customer has the balance connector headphones or can modify the headphone to balance connector, choice would be the NFB-28. Summarize Fully balanced design built by discrete analog stages . Output for headphone (4-pin XLR or 1/4") and DAC (fixed output) with preamp (variable output) Non- feedback ACSS analog output stage . Large R-core transformers and Hi-fi grade parts like DALE resistors, WIMA caps . Total of 6-groups of PSUs are used to purify the power supply , the analog amp has discrete PSU (power supply ) Four-channel 100 steps digitally controlled relay-based volume control avoid channel imbalance and improves sound quality . Supper Exponential Volume Characteristic with Fast / slow selection, easy match the volume with very different sensitivity headphones / speakers 4 digital inputs: USB / Optical / Coaxial RCA / I2S 2 analog inputs: XLR / RCA (The RCA input can be converted to XLR output natively without extra converter ) DAC output: XLR / RCA / ACSS Headphone output : 4 pin XLR / 1/4" (6.3MM) SE User can change the digital parameter settings 4 types gain modes to drive the high and low sensitivity headphones very easy .

Price: ( Exclude shipping cost) NFB -28.28: USD750 (ES9028Pro) NFB -28.38 TCXO version: USD880 ( ES9038Pro, Femtosecond TCXO ) NFB -28.38 Full clock upgrade version: USD910 ( ES9038Pro, Femtosecond Accusilicon upgrade the stock clock and Femtosecond Crystek *2 upgrade on USB interface) Please send your address, name to audio-gd@vip.163.com get the quote. Accusilicon clocks: Crystek clocks: Since Dec. 2018, the model had upgraded two pc OPA+transistor serve PSUs to improved the sound quality