Inferior sound quality when using Audirvana with an RPI endpoint

Hi,

I’m still experiencing issues with sound quality in my system. I had already described a part of it here: Random sound quality & ASIO audio stream path.

To put things back into context, I decided to buy a Raspberry Pi 4 and use it as an endpoint to keep the PC away from my hifi equipment and avoid disturbances (fan noise, etc). However, now I realize the sound quality is definitely not as good as it used to be when I was connecting the PC directly to the DAC, with the proprietary TEAC driver.

So my question is: what may cause a difference in terms of sound quality between the current and the previous configurations described below?

  • Configuration 1 (direct path): PC running Audirvana with a direct USB connection to the DAC (ASIO Driver from DAC manufacturer installed).
    The music was very dynamic and playing loud, with each instrument sharply defined. The band was basically playing live in front of me with a large sound stage and superb imaging.

  • Configuration 2 (streaming): RPI4 endpoint running Volumio, retrieving the audio stream from Audirvana on the PC via ethernet (local network from my Internet Service Provider box, which includes a router with 4 switches to which the PC and the RPI are connected, in addition to the TV player and the NAS) and connected to the DAC via an USB connection.
    The source now sounds flatter, lacks definition and dynamics, as if it was downsampled at some point.

Could this be due the one of the following:

  • Poor quality of the switching power supply of the RPI, delivering inaccurate USB output voltage to the DAC (should I get a linear PS)?
  • Volumio reprocessing audio? There are several settings that may affect sound quality such as volume parameters (isn’t Volumio supposed to be just a passthrough and BitPerfect device when used as a transport)… I had used Dietpi before that and sound quality was clearly not as good as Volumio (and did not support DSD), although both were supposed to deliver BitPerfect audio.
  • Could the switch bandwidth be insufficient, losing data on the way? Maybe I should get a separate router…

I realize that the second (current) configuration uses many devices and an extended signal path, it is definitely not as straighforward as PC > DAC and each may introduce jitter and interferences. It seems something is lost or degraded during the streaming process.

That thread actually described the same symptoms: Sound quality compared between local and streaming

Could you help me find out what the problem is and what could optimize my system?

Have a great weekend!

It’s the USB that sucks on RPi, at least for audio. You might want to put a HAT on the RPi and use SPDIF.

Another option is to use the Allo USB Bridge, though I’m not sure if they sell the HAT separately. You may need to purchase the Sparky SBC and the HAT together:
https://www.allo.com/sparky-eu/usbridge.html

I was waiting for someone to reply who actually has some experience with the Raspberry Pi. I believe there is a single shared USB bus and adding a single USB 2.0 component will significantly affect throughput overall. If you have a wired keyboard or a mouse connected, that could create a major bottleneck for USB throughput. If so, you might want to consider adding a Bluetooth keyboard and mouse instead as that should free up your USB controller to give you true USB 3.0 throughput. However, if your DAC has an Ethernet port and supports UPnP, you might want to try connecting over your gigabit LAN.

Really? The reason why I bought an RPI is that plenty people said it is better to plug an external DAC into a dedicated RPI with clean USB output and power management than plug the DAC into a computer that runs plenty processes and is prone to electrical pollution… Maybe I should buy a 3-meter USB cable to connect the computer to the DAC and sell the RPI???

The RPI 4 has two USB 2.0 and two USB 3.0 ports. I’m only using one of the USB 2.0 ports. No need to connect a keyboard or mouse since the Volumio OS is running on the RPI.

Clean power to the dedicated HAT. You can power the RPi through the HAT.

Powering the RPi with clean power won’t bring much improvement.

I have no experience with Volumio. Can I assume you’ve posted this same question to the Volumio community forum? I would think you’d find more expertise there than on an Audirvana forum. You haven’t told us anything about your DAC except for the drivers employed on your PC setup. I suspect that Volumio doesn’t recognize the DAC and is defaulting to a basic 16/44.1 configuration. Again, if your DAC supports a network connection, try connecting to it via UPNP, but then again, if it did, you could’ve done that from your PC.

Hi,
I am using RPi 4 running Volumio and have an USB connected DAC. In my configuration, the RPi is powered by an audiophile-grade PSU (Allo Nirvana). The DAC (Topping e30) is powered independently using a second power output on the Nirvana. The USB connection uses an active filter, rebalancer and reclocker (iFi iPurifier 3). The SQ is excellent, especially the introduction of the iPurifier was a major step up. I have opted for an external reclocker instead of using an internal HAT with reclocker (like the Allo DigiOne Signature) and coax connection between the HAT and the DAC to not introduce the 192/24 limit for the bitrate when using coax. iPurifier also provides an active noise cancelling filter, so I believe this configuration is superior when comparing to the DigiOne Signature.
If you are not using the RPi in other configuration, only for streaming from PC via Audirvana, you also might consider using RoPieee XXL which provides an UpNP renderer w/o all the Volumio overhead. I am using RoPieee in my office configuration with Roon and I found it at least more stable, but have not compared the SQ with the Volumio setup.
R.

On a second thought, if SQ was your reason to go for RPi, you might also consider to use the iPurifier in your Configuration 1 and probably observe SQ improvement…
There are other external reclockers. A friend of mine uses the Matrix Audio SPDIF 2 on a high end system with an R2R DAC for example.

Oh,alright, I thought using the RPIs USB output was sufficient to connect to my external DAC with the finest quality. I thought the hat was necessary for those who wanted to add a DAC to the RPI or other output types (spdif, etc). Thanks for clarifying. I was wrong from the very start then! Which separate hat and clean power supply (linear?) would you recommend for the RPI4? Are you confident it would work better than using the PC’s USB output (which is in theory heavy polluted electrically)?

No, I haven’t because Volumio is supposed to be a passthrough endpoint when used in that configuration. And then when I check Volumio settings the other day I realized it may (or may not) reprocess audio stream. My DAC is the TEAC UD-503 model and it is recognized right away by Volumio, and supports the correct bitrates.

Check out the Allo USB Bridge, but I’m not sure if it’s sold separately still.

https://www.allo.com/sparky-eu/usbridge.html

If you don’t care about DSD, you might want to check SPDIF output HATs. You’ll have more options there, like HiFiBerry:
https://www.hifiberry.com/shop/boards/hifiberry-digiplus-standard-version/
https://www.hifiberry.com/shop/boards/hifiberry-digi-pro/

Thanks for your reply. The problem is that RopieeeXL doesn’t support DSD and didn’t sound as good as Volumio so I gave up on that one :frowning: Is your PSU able to deliver enough current to be up to the RPi 4 specs?

I couldn’t live without DSD :wink: So what are my options to get a separate dedicated audio USB output hat I can add to my RPi4 and feed with a super clean PSU?

Well I am using RoPieee XXL with Roon and it perfectly supports DSD (provided your DAC does support DSD as well), but I haven’t done any A/B comparison with Volumio. Allo Nirvana ports are both rated 2.85 A, which is enough for RPi in my setup. I can not comment whether that is enough to drive RPi with a display installed if you are looking to do that. The Allo Shanti has on port rated 3A and the other 1A.

Get the Allo USB Bridge, including the Sparky board:
https://www.allo.com/sparky-eu/usbridge.html

Or even better go for the USB Bridge Sig.:
https://www.allo.com/sparky-eu/usbridge-signature-pcb.html

Other than that you’ll have to look at commercial USB bridge products like Sonore ultraRendu, SOtM, Auralic, …

Just to clarify… from Allo Nirvana page
Nirvana has only one output at 2.85A/5V

No load is 5.2V , 2.85A 4.97 to 5.03V

We provide USB connection for convenience only it’s not a second, galvanically separated output.

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Aha interresting… I am powering the RPi and the e30, whereas e30 consumes only about 0,5 A… Then powering the RPi display might be a problem…

This thread makes me realize that adding an intermediate and costly device would complicate the signal path and might be useless, since a network streamer version of my DAC exists: http://audio.teac.com/product/nt-503/

Replacing my current DAC (UD-503) with the Network version (NT-503) would actually solve all issues and cost me much less, with no need to bother about the quality of the USB output and cables since the signal would be sent right into the DAC through ethernet.

What do you think? Does anybody known if Audirvana can access network players like this just like Raspberry Pies or other network devices?

Most likely it will work, since the network player supports DLNA.