The Singxer SU-2 is the most recent of the Singxer DDC family, but sits in the middle in pricing, and in theory, performance.
The SU-6 (measured here: https://goldensound.audio/2021/08/01/singxer-su6-measurements/ ) was an exceptionally high performing DDC, so that could hopefully bode well for the SU-2.
BUT, this is not a stock SU-2, this is the Kitsune-Tuned edition which features quite a few hand modifications to the stock design.
From KitsuneHifi’s site:
“KTE SU-2 is a Kitsune Tuned Edition of the very popular Singxer SU2 and it includes a total of five regulators (Three discrete regulators(w/heatsinks) and two surface mount regulator upgrades), one for 5v PSU, and the others for the 3.3v for digital outputs and two surface mount regulators for the clocks. Mundorf Supreme 9.5% silver solder used for all components upgrades. OSCON Ultra low ESR caps, MB mods, air dialectric SPC solid core hookup wire, silver HifiTuning fuse, Vishay film caps, Kycon High Retention USB connector to improve connection quality/impedance, graphene enhanced contacts for IEC, Fuse and connections, internal connectors and usb connector. Surface mount regulators are upgraded for the two Femto clocks with better than 6uV output noise. Vishay Film caps used in PSU and ultra high performance discrete regulators for both 5V(PSU) and 3.3V(digital outputs) – 3.2uV output noise or less (lower voltage is less noise… 3.3v is approx 2uV output noise), -125db PSRR (power supply rejection ratio) compared to the stock regulators @ 150uV output noise and -70db PSRR approx.
KTE SU-2 has custom Solid copper emblems. Each unit is individually serialized. Each unit is modded by hand and burned in for 72 hours before returning to the customer.”
So, quite a few changes then! And what I can say is that taking a look at the inside, the modifications are done in an exceptionally clean manner. You honestly would not know that this had been modded unless someone told you (or you looked at the internals of a stock SU-2). The soldering is excellent and the caps look like they belong there.
The only bit that stands out as perhaps ‘obviously not stock’ is that the beefier regulators have quite large heatsinks compared to the stock versions.
This device also has a benefit over the SU-2 in that it can handle DSD1024 and PCM768khz. Whereas the SU-6 (and other great DDCs like the DI20HE) can only do 384khz.
On the rear I/O has just about everything you’d need. IEC power in, a modified high-retention USB connector, I2S, coax, BNC, AES, and a 10mhz input for external clock use.
The only thing missing would be RJ45 I2S, but the standard for I2S seems to be HDMI by vast majority anyway.
There are also switches on the underside of the unit to adjust the pinout of the i2s output to fit any DAC.
– Audio Precision APx555 B-Series Analyzer
– AudioQuest Carbon Coaxial Cable (1.5m)
– Intel PC via ifi iGalvanic 3.0 and iUSB 3.0 as USB source
– 44.1khz and 48khz real music played through device during measurement
– Coax output used unless otherwise specified
Content and analysis made possible thanks to support from https://headphones.com, and https://patreon.com/goldensound supporters
To measure jitter, the device is connected to the digital input of the APx555, and the analyzer is set to analyze jitter, not audio content.
These measurements do not show audio/analog info, but instead show the spectrum of jitter, ie: time-domain inconsistencies.
This is the primary factor that a good streamer or DDC will seek to improve.
Very good performance here for both 44.1khz and 48khz. Only a small margin behind the SU-6 in RMS/Peak jitter performance.
(SU-6 had 75ps RMS and 224ps Peak jitter values)
There are a few jitter spurs in the 1-10khz range which are not present on the SU-6, though this isn’t uncommon and similar behaviour is visible on other great DDCs like the Wavedream NET.
In terms of jitter, realistically it and the SU-6 are fantastic, and it’s going to come down to whether the ability to use 768khz for tools like HQPlayer, or slightly better native 44.1khz/48khz performance is more important for you.
Noise however, is very impressive and does beat the SU-6 outright:
Absolutely stellar performance here, with the 50hz spike only getting to about 1.5uV!! Compared to the SU-6 at ~2.5uV. And RMS/Peak noise being the lowest I’ve seen so far.
How much of this is down to the product itself and how much is down to the various upgrades to capacitors, regulators etc that Kitsune has done, I can’t be sure without a comparison to a stock unit. But whatever it is, it’s working!
AES Jitter performance is actually a bit better than coax SPDIF:
So in summary, the KTE SU-2 is excellent. Truly spectacular performance with the lowest noise I’ve seen from a DDC and top notch jitter performance.
Whether this or the SU-6 is the better choice given the similar pricing will I think come down entirely to whether you’d make use of 768khz support or not.
If you would, get the SU-2.
If you wouldn’t, then the SU-6 edges out the SU-2 for jitter performance.