SDA-2C ( Advanced Version ) – HiFi NOS Native DAC and Headphone Amplifier
The SDA-2 decoder is a high-performance HiFi-class audio decoding amp preamplifier developed by our team . It uses XMOS’s latest xCORE-200 series chip as the USB Audio solution, and uses the AKM497 of the AKM third-generation DAC as the DA. The conversion chip, AK4118 as a digital audio input receiver chip, uses STM32 as the control of the whole machine, Xilinx’s large-scale FPGA as the processing of the clock system and digital audio stream. The amp part adopts 4-way full balance design, independent discrete class A amp drive circuit; the front stage output adopts analog pre-stage design, which is not the way of digital attenuation affecting sound dynamics; has rich input and output interfaces, including standard USB2 .0 input interface, SPDIF coaxial and AES balanced input, analog XLR balanced output, analog RCA output.
PCM supports up to 384Khz, DSD uses native direct solution technology, supports up to DSD512 , and all interfaces support DSD decoding.
The DAC chip adopts AKM’s flagship DAC AK4497EQ; the DSD adopts the native direct solution mode. The DSD digital stream does not pass through the internal digital filter and modulator, and works in the NOS mode. The PCM can also choose to work in the NOS mode, which is in line with the HQPlayer design concept. .
SDA-2 is the first decoding amp preamp product we developed, mainly using the following four main technologies:
1, USB part uses our first generation isolation technology: SCIT technology (Singxer capacitor isolation technique), SCIT technology is a full isolation technology (ground isolation), high-speed signal using 150Mbps isolation chip, low-speed signal using optocoupler isolation It can completely isolate the interference from the PC; the USB version of the high version can basically reach the level of the SU-1 independent digital interface.
2, source synchronization technology and FPGA shaping technology, re-shaping the isolated I2S signal; thus eliminating the additive jitter caused by the isolation chip;
3. The self-developed clock system uses a femtosecond crystal oscillator as the local reference clock;
4, 4 way class A discrete amp circuit, full balanced amplification of 8 patch transistors per route.
Sample rate supported by each input interface:
PCM: 44.1KHz, 48KHz, 88.2KHz, 96KHz,
176.4KHz, 192KHz, 352.8KHz, 384KHz
[Which USB and I2S support all sampling rates, S/PDIF supports up to 192KHz]
DSD: 2.8 MHz (DSD64) – DoP, native
5.6 MHz (DSD128) – DoP, native
11.2 MHz (DSD256) – DoP, native
22.5792 MHz (DSD512) – native
[USB and I2S support all DSD formats, S/PDIF and AES/EBU support DSD64 DOP mode]
Bit width: up to 32 bit over I2S output
Up to 24 bit over S/PDIF
Electrical standard of each interface:
1. USB input socket is standard USB-B type female socket, USB power supply range is 4.5V-5.1V;
2. SPDIF interface inputs standard S/PDIF signal, input impedance is 75 ohm, AES input impedance It is 110 ohms;
3, the power input is 115V/230V AC, and the internal 30W O-type transformer is used for power supply;
4. The I2S input is LVDS level in the form of HDMI interface, compatible with SU-1 interface;
Analog Output Performance:
Output Level (0dBFS):
PCM: RCA single-ended output is 2V RMS, XLR balanced output is 4V RMS
DSD: RCA single-ended output is 1.8V RMS, XLR balanced output is 3.6V RMS
Output impedance(backside): 22 ohms (RCA single-ended) / 44 ohm (XLR balanced)
(XLR 4pin BAL) headphone impedance is less than 2Ohm
(SE 1/4) headphone impedance is less than 1Ohm
Frequency response: 20-20kHz +/-0.2dB
Signal to noise ratio: 125dB
THD+N (1kHz, 0dBFS) 0.0002% at fs=44.1Khz(PCM)
THD +N (1kHz, 0dBFS) 0.00023% at DSD256
dynamic response (1kHz, -60dBFS) 125dB
channel separation >125dB
Balanced output noise floor: 2.2uv RMS
Amp balance maximum output power 3480mW@30Ω, 0dBFS
Distortion of the amp balanced output, 0DBFS, fs=44.1Khz (PCM)
75Ω load THD+N -110dB
600Ω load THD+N -111dB
The following are AP measured data, all are DAC balanced fixed level output mode, filter SHARP,fs=44.1Khz (PCM)
1. Very clean 1K FFT with only 2-5 harmonics, no high harmonics and other spurs
2. Ultra Low noise floor, about 2.0uV
3. 20-20k Frequency response, perfect
4. Excellent distortion performance, THD+N sweep test keeps the whole frequency band below 0.00033%
5. Excellent signal to noise ration (SNR), measuring SNR at 125.6dB
6. Rapid Dynamic response, DNR reaches 126dB
Sam aka Comzee (verified owner) –
Have had the Singxer SDA-2 for two weeks now. Took about a week of burn in to settle in and sound more liquid and tonally complete.
This is an astounding device as the price point. The AKM4497 implementation is superb.
The highlights in my opinion are:
#1 USB implementation that doesn’t suck (better than most $2k+ dacs USB). I used a Lynx AES16e for digital input, and found no improvement, maybe even a slight decrease in performance. This one feature alone can save you kilobucks on digital nervosi.
#2 The built in Class A amp is more than sufficient for almost any headphone, except the absolute most demanding like the HE6. I have it powering my HD800 and it has a vice grip on dynamics and control. The headamp is also fully balanced output, if you have 4pin XLR headphone cable to go with it!
#3 The AKM4497 DAC is technically masterful. Great resolution, dynamics, imaging, clarity, air to the sound. It has great synergy with the built in headamp.
#4 The filters add a great touch to an already great AIO. The “NOS” filter is the best NOS mode I’ve heard on a DAC. The OS filters are excellent if you prefer OS sound.
For me, I really love this device as an AIO. All the components synergize extremely well together. From the USB input, to the DAC, to the headamp, all aspects combine flawlessly for a no nonsense experience. Just plug in the SDA-2 and forgot about all the other stuff, and start listening to music. It’s that good as an AIO. Everything just works together, no components bottle-necking each other.
I would rate this above any budget build, products such as SDAC/THX AAA 789/Eddie Current ZDT Jr./Lquid Carbon X/Modi3/ODAC. Basically forgot about stringing together a Mass Drop build, because SDA-2 will sound more cohesive and complete.
If you want close to top of the line performance at a fraction of the price, in one unit, and don’t want to deal with all the other crap that comes with it, this is a no-brainer.