First of all, I want to clarify that I’m not an audio expert—just an enthusiast—so don’t expect anything too scientific or magical from what I’m about to share. For a long time, I used an old SoundBlaster X-Fi (honestly, nothing special) connected through its RCA outputs and adapted to 3.5 mm. Eventually, I decided to upgrade to a FiiO BTR15 DAC, expecting a clear improvement. To my surprise, with newer and supposedly better hardware, I couldn’t initially reach the audio quality I was used to with the SoundBlaster.

Spoiler alert: this journey turned out to be way crazier than expected. Audio is not always as “plug and play” as one might hope. After digging deeper and carefully reviewing configurations, I finally found a few parameters that made a very noticeable difference in sound quality.

Here are my initial findings:

• Forget Bluetooth. The 2.4 GHz band is simply too crowded to transmit audio at the quality I’m looking for. Even though it claims to support up to 96 kHz, I noticed less blending and better instrument separation at 44.1 kHz over USB—both on my computer and on Android.
• Dual DAC mode: don’t forget to enable it in the FiiO Control app (Android). On paper, it should improve audio quality. In practice… don’t expect miracles.
• 3.5 mm vs balanced 4.4 mm output: (waiting for the cable) this should greatly improve the sound. When you buy a DAC, nobody really explains—at least not to beginners like me—that balanced output is not only about more power; it can also improve overall audio quality. Something similar happens when you compare the SoundBlaster’s headphone output to its RCA output: you don’t just get more power, you also get noticeably better sound quality at lower volumes (that was a big “aha” moment for me).
• 44.1 kHz? Most people listen to 44.1 kHz audio. I mostly use Spotify and a few FLAC files, all in 44.1 kHz. Many comments online claim that the operating system will automatically set the DAC to the correct sample rate, but that’s not entirely true—you can manually change it, and it can make a real difference.

What did I discover about 44.1 kHz?

Maybe other operating systems handle this better, but on Linux this is not always automatic. You can manually change the sample rate sent to the DAC, and in my experience this significantly reduced blending and improved clarity even further.

How to change the transmission rate in Linux

It’s actually quite simple (though maybe not for everyone). Here’s how I did it on Fedora.

By default, Fedora doesn’t have an /etc/pipewire directory, so first you need to create it:

cp -a /usr/share/pipewire /etc/

Next, create a configuration file for the sample rates:

cd /etc/pipewire/pipewire.conf.d/
cp -a ../pipewire.conf.avail/10-rates.conf .

Edit the file:

nano /etc/pipewire/pipewire.conf.d/10-rates.conf

The file should look something like this:

context.properties = {
    default.clock.rate          = 384000
    default.clock.allowed-rates = [ 48000 44100 96000 192000 384000 ]
}

Now do something similar for WirePlumber:

cd /etc/wireplumber/main.lua.d/
cp -a /usr/share/wireplumber/main.lua.d/50-alsa-config.lua .

Edit the copied file:

nano /etc/wireplumber/main.lua.d/50-alsa-config.lua

Uncomment and adjust the following lines (audio.rate and audio.allowed-rates):

["audio.rate"]          = 384000,
["audio.allowed-rates"] = "44100,48000,96000,192000,384000",

After restarting your computer, the audio quality should be noticeably better.

In my case, even when the source was only 44.1 kHz, increasing audio.rate improved the overall sound to a very acceptable level. That said, the SoundBlaster X-Fi using its RCA outputs was still slightly better at this stage. I’m still waiting to test the balanced output on the FiiO (test pending).

Some additional recommendations:

• Do not connect the DAC through an overloaded USB hub—it may not receive enough power to operate properly.
• Keep the DAC away from strong electromagnetic sources (Bluetooth, Wi-Fi, GSM devices, etc.).
• In Spotify, set downloads and streaming to the highest quality and disable “auto adjust quality.” Be aware that this will use more data and may increase buffering times.
• FLAC files or higher-quality/Hi-Fi streaming services make a huge difference.
• If you lose audio after these changes, try lowering audio.rate and default.clock.rate (192 kHz, 96 kHz, etc.).
• Use pavucontrol and select the FiiO BTR15 “Pro Audio” profile.
• And please—don’t forget to use the balanced output.