Holo Audio Red vs Singxer SU-6

[hardcore]

I just got the Holo Audio Red at home to test in my setup and can finally compare it to my Singxer SU-6 as a digital source to the Devialet 1000 Pro using AES input.

Sound Quality:

The Red sounds pretty good in DDC mode. This was using USB input from my PC. It sounds clean and natural.

Next, using the Red running in streamer mode (Red OS using ethernet source) and using its own digital output sounds very nice. I tested with the AES output. A detailed, open sound with a natural tone. Slightly clearer and more nimble sounding compared to using DDC mode from the PC.

Finally, I tried the Red running in streamer mode, with USB output to the Singxer SU-6, which then used AES output to the Devialet. Wow, the output from the Singxer sounded airier with smoother highs, compared to using the AES output directly from the Red.

Adding another tweak into the mix, I used an ifi iDefender+ to inject clean USB power from an LPS into the USB cable going to the Singxer and this sounded even better.

TL;DR: The Red sounds good as a Streamer and DDC. Adding the Singxer to the Red via USB output actually brings an airier soundstage and smoother highs than the Red's own AES output, whilst preserving the natural tone of the Red. The Red's AES output sounds slightly punchier while the Singxer's is smoother and has a bit more depth to the soundstage. It's best to listen to see which you prefer. Both are similar in detail and sound good.

Unexpected feature!

The Red can work as a DDC and Streamer at the same time if the ETHERNET and USB INPUT are connected, and the USB OUTPUT is also connected to another DDC or DAC. You must also have the micro SD with Red OS inserted. For example, this is my test setup:

[PC] --- USB In ---> [Red] --- Optical Toslink ---> [Devialet]
+
[Network] --- Ethernet ---> [Red] --- USB Out ---> [Singxer SU-6] --- AES ---> [Devialet]

Now, in DDC mode, the audio is sent to the Optical output of the Red.
And for streaming services, e.g. Tidal Connect or UPNP, the audio output is sent via USB to Singxer which outputs AES.

Now I can switch between both modes on the Devialet by just switching the inputs. Excellent!

This fits my use case where for videos, games and general PC use, I use DDC mode for audio.
And for more serious listening I can use the Streamer mode via UPNP, Roon, Tidal Connect, etc.

Limitations of the Holo Audio Red:

The Red has only a USB 2.0 output, which doesn't work with my Fibbr Alpha USB cable which requires a USB 3.0 output. Still sounds great with a regular copper AQ Carbon USB cable.

As of today (March 2025), the Red OS streamer support for Tidal Connect is limited to CD quality. It does not support Hi-Rez / Max quality. The Red allows you to use other OS like Volumio (paid) which supports Tidal Connect at Max quality.

[ada]

Hello, it seems like you are making a great progress on the digital inputs with good devices in hand. Could you also compare the PC to Singxer (USB) to Devialet (AES) option with the other combinations you tried.

[Vivialet]

I have also played around with my digital fronend in the past few month. In the last years I have used a NUC8 i7 with an ethernet connection (lots of stuff, expensive routers, LWL converters, ...), USB was always inferior.
Now I'm using a Minisforum UM 790 Pro via USB4 which is by far surpassing my old PC/Ethernet in terms of SQ. I also use a Holo Red which is connected to the Devialet with a combination of a Wireworld Supernova Toslink cable and an ifi SPDIF Purifier 2 connected to an SPDIF input. This is the best combination I tried so far.
Microsoft has also updated the Windows 11 USB drivers in the last updates, I think this really makes a difference.

[hardcore]

Hello, it seems like you are making a great progress on the digital inputs with good devices in hand. Could you also compare the PC to Singxer (USB) to Devialet (AES) option with the other combinations you tried.

Hi @ada, the PC ---USB---> Singxer SU-6 ---AES---> Devialet is my regular setup before testing the Holo Red.

I have done many tweaks to the PC:
- Use an optical USB cable between PC and Singxer to provide galvanic isolation. This is a Fibbr Alpha USB cable which is fully fibre.
- Use a HDMI filter device (ifi HDMI iSilencer+) to reduce electrical noise from the TV, which makes quite a difference in sound.
- Use a USB Ethernet adapter and isolate the USB ground and 5V power using ifi USB iDefender and separate power supply.
- Disabled USB interrupt moderation in Windows (a gamer tweak called the xHCI IMOD tweak), this helps too.
- Choose the best sounding USB port on the PC, different ports can sound very different.
- I plan to replace my optical HDMI cable with a new pure fiber HDMI cable, which will provide total isolation from the TV.

Comparing the PC to using the Holo Red as a streamer, the PC sounds slightly darker, and the soundstage is slightly smaller. The Red sounds more nimble and clean with better microdetails.

On the PC, the sound changes after Windows has been running for a while. The PC sounds best after a reboot while the Holo Red sounds good consistently.

Comparing the Red's AES output with the Singxer connected to Red's USB output, the Singxer has a slightly airier soundstage and smoother highs which makes it sound a bit more relaxed.

Now with the Holo Red --- USB --> Singxer SU-6 --- AES --> Devialet, this is the best my system has sounded so far. I'm going to test the Red for a few more days and I'm tempted to get it.

The sound of the PC and Streamer changes a lot depending on the network connection. I made some big improvements by adding fibre ethernet isolation on the network, and this improves the sound dramatically. The network switch also affects the sound, experiment with different ports on the switch as they sound different.

I changed all my ethernet cables to solid core *unshielded* cables. In the past, I used shielded ethernet cables, but they color the sound making it sharp and edgy. Changing to solid core unshielded cables was a revelation. A few friends tried this in their systems and all had big improvements in sound.

[hardcore]

Experimenting with different OS on the Red, I've tried Moode and Hifiberry with the unofficial Tidal Connect plugin. Interestingly, playing the same music on the stock Red OS in performance mode sounds much better. I noticed in the Red OS image that they do some CPU core isolation, so it appears that the OS is also optimized.

Sadly the unofficial Tidal Connect docker image also does not support Tidal Max or Hi-Rez. I might try Volumio later.

[hardcore]

I've received my new full optical HDMI cable and it works well. Highly recommended in case anyone is interested:
https://ruipro.store/collections/all/pro...hdmi-cable

Using it between my PC which has an RTX 3090 GPU and an LG OLED C9 TV.

So now that the PC is optically isolated from the TV, I've done more comparisons between:

PC --- USB --> Singxer --- AES --> Devialet
and
Red --- USB --> Singxer --- AES --> Devialet

The PC sounds remarkably good now. The Red still sounds better overall. Red has a bigger soundstage than the PC, the mids are more forward, and it sounds overall clearer. The PC sounds a bit darker.

[audio_engr]

After experimenting with a few Streamers with my 440-Pro CI, I finally settled in with the Wattson Audio Emerson Digital powered with Farad Super3 and using Audioquest WILD AES Digital cable. Whilst I am in between breaking-in both the Farad and the Emerson Digital, I must say its a great change for the better from my earlier days of streaming directly using Ethernet into the Devialet via my etherRegen.

[markush]

Having compared several streamers over the last years the Holo Red is amazing. For best performance try use the HQPlayer OS and use the Red as NAA endpoint.
Also a good power cord and a fuse upgrade will be very noticeable improvements.

[hardcore]

Just discovered that the BubbleUPNP App supports streaming Tidal to UPNP, and it supports Hi-Res FLAC too! Finally, a way to get Tidal Max quality on the Red and other streamers. Hi-Res Tidal is not enabled by default on BubbleUPNP though, you have to enable it in the menu: More > Settings > Local and Cloud > TIDAL > WiFi/Eth audio quality.

Even at CD quality though, playing the same song from Tidal over UPNP sounds slightly more open vs Tidal Connect on the Red.

Also found that BubbleUPNP can play YouTube Music via UPNP, even better! Finally can stream those Scary Pockets, Stories and NPR Tiny Desk concerts.

[hardcore]

Installed the Red in my friend's system today, who is using a PS Audio Directstream DAC feeding MBL monoblocks.

We had to first open up the Red to switch the input voltage to 110V (it has a switch next to the transformer for this) and change the fuse to the appropriate rating for 110V. The build quality of the Red is out of this world, really solid and the internal casework is very elaborate. Had to remove more screws than expected to access the transformer, but it wasn't too difficult to do.

Some interesting findings:

The Red's I2S output is not fully compatible with the PS Audio I2S input. It works fine for DSD signals, but for PCM signals, the PS Audio DAC will apply a pre-emphasis filter which rolls off the highs. This means you would want to use the AES output for PS Audio DACs.

We compared the sound to the Singxer SU-6 acting as DDC, connected to the USB output of the Red. The Singxer was connected to the PS Audio DAC using I2S which works fine (no pre-emphasis issue with PCM signals). Without any tweaks, the Singxer sounded different but was not that impressive.

Next we added the ifi USB iDefender to inject clean 5V from a linear power supply into the USB cable feeding the Singxer. This significantly opened up the sound and now the Singxer sounded very clearer better than the Red's direct output. Bigger and deeper soundstage and smoother highs.

So that's the final configuration for his system:

Red --- USB (+5V from Linear PSU) --> Singxer --- I2S HDMI --> PS Audio Directstream