rPi 4 - USB audio connection - known quality issues?

Plex Players Streaming Devices
1

I love my music to sound good, or at least, as good as I can get it. No, I am not the type to spend serious $$ on cable upgrades…

I installed PlexAmp on the Raspberry Pi 4 and connected it with a USB on a rather good DAC. I listened, and noticed some sound issues - pops and what sounded like distortion. The soundstage is also less pronounced. Doing my research, I noted that there was a significant issue with the Pi 3 model and USB noise - but it would have been resolved with the Pi 4?
Keen to solve this, as PlexAmp is really fantastic (BTW: my computer in my office is linked to the USB to a DAC, and no issues, with pops or distortion - so it is not PlexAmp, nor USB). That leaves the Pi, and the DAC in my living room - the DAC has never been used with the USB connection before, only TOSLINK and Coax digital inputs.

PlexAmp over Chomecast (via TOSLINK) to the DAC in the living room sounds fine (except for the gaps).

I have my eye on a Digi+ HAT from HiFiBerry - will that solve the issue? - also - do these HAT’s fit the Pi 4 and Pi 3, or do I need to specifically buy for the model I have (4 model b)?

2

what are your current playback settings for plexamp on the pi?
(“pi IP address”:32500 under settings → playback)

for high quality playback with least risk of distortion due to clipping/limiting, recommend the combination of no loudness leveling, no limiter, and no EQ as a starting point (or if loudness leveling is needed, set preamp gain to 0 dB)

3

Look at encoding too: I have an iqaudio dac+ and I think aac has problems when flac doesn’t.

4

Thanks-

I have tried this. On my Pi with loudness levelling, limiter, and EQ off (which is my default start position) - it is very distorted.
On my desktop (also connected via USB to a DAC), all on or off, no issues - it sounds fantastic.

Playing PlexAmp to my Chromecast Audio via optical to the same amp as the Pi, no issues.

5

The encoding is FLAC.

Since this is isolated to the Pi only, I think it is the device USB - I am purchasing a HifiBerry Digi+ HAT, I assume these fit universally on Pi’s? Or do I need to purchase one specific for the Pi 4 Model B?

6

Should be fine.

7

Correct, the spdif hat you’re referring to is also compatible with the pi4

Note, the pi4 doesn’t share controller bandwidth between USB and ethernet (as did the pi3)

If this is the first time you’ve used the USB input for this DAC, you might want to look at its capabilities (lsusb -v) and any settings (alsamixer) to see if anything there might explain the distortion

8

Just to update anyone interested- the HiFiBerry Digi+ arrived, installed like a charm on the Pi4, and the sound quality is FANTASTIC!

Thanks to everyone that took the time to assist with this!

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