Optimal C-3PO settings

Just wondering what settings people are using with the new C-3PO software. I have a dac that can cope with 192/24 files but find these settings sound best

Upsample PCM to 96k
Output bit depth 3x24
Loudness +5db

Welcome others insights

If you are re-sampling I wouldn’t have everything going to 192, you would want to have the rate family covered. So 44.1 goes to 176.4 and 48 goes to 192.
Or if 96 is for you I would ensure the 88.2 is also covered.

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Hello Mark, and one line up does not need to be ticked? With bit output? For example tick 24 for DACs with max. 24/192 resolution?

My recommendation would be to check all the PCM rates that your DAC supports. The following setting would then ensure that resampling picks the correct rate.

I think Antipodes is working on improving the C-3po function or making it more understandable. I would say without C-3po it sounds most natural, more honest. Nevertheless, with C-3po it sounds calmer and more resolved. But since my Merason DAC doesn’t have a display, I can’t tell what sample rate is actually playing at the moment. So I have to trust my ears. I have the feeling that no matter where I tick something, something changes, but what is happening is not self-explanatory. For the next upgrade, please try to describe each function better, where must be ticked when using different DACs. And what would be good would be information on the tablet, during playback or something, what is actually being upsampled. Original info on the left, upsampled info on the right…Well, I wouldn’t write off the C-3po function. Just improve it and make it more self-explanatory.

I’m not sure I understand, my comment was aimed @Vorrah but as kennyB alludes there is more than one way to skin a cat, but if you select 24/192 only, then a 44.1 will be sampled to 24/192, which is not a direct multiple of 44.1, and interpolated results will be used, which may contain errors.
44.1x4=176400 a direct multiple
48x4=192 a direct multiple
Of course you can set it to whatever you like, but to keep the original files integrity, the direct rate family should be used.

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C-3PO doesn’t have a sound per se. It’s actually just a “helper” that allows other open source libraries to act on the song being played. I think it might actually be ffmpeg that does the transcoding based on the settings saved in C-3PO.

The sound quality one will hear from resampling music with dsp apps like HQPlayer or ffmpeg can be limited by what the DAC itself does as far as resampling. In your case though, it does appear as though your DAC is a true NOS DAC, so this would be the ideal candidate to leverage what C-3PO can bring.

I would recommend experimenting with the different filter options as one may be more to your liking than others.

The Merason DAC-1 MK2 is a NOS DAC.

Mein Gott ist das verwirrend. Ich glaube ich schalte C-3po besser ab, solange ich nicht weiß, was da passiert. Ich sagte ja auch, egal wo ich Häkchen setze, mein DAC spielt es, aber ich weiß nicht was er abspielt. Ich sehe keine Samplerate. Ich sehe kein Upsampling Ergebnis.

This is spot on. The goal should be to make sure the upscaled frequency is an even multiple of the original frequency. There will be losses if one isn’t careful to do this.

Show me a reading, a result of the current sample rate. Current issue. Then I can tell you if it fits.

My DAC can display the sample rate. The results from resampling are easy to predict as C-3PO will make sure the settings are applied. Configure the settings as recommended and you won’t have to worry about seeing the results.

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So you are the developer of the software and confirm that the software does everything right, correct? In addition, the software is probably being worked on in the background because it is not working correctly. Otherwise Antipodes wouldn’t advise almost everyone to deactivate C-3po. It doesn’t even play my FLAC from SSDs. For my DAC Merason DAC-1 MK2, no display, maximum resolution 24/192, digitally synchronous 176 kHz not possible only via USB, someone must be able to tell me what the correct output sample rate setting is for my NOS DAC. Don’t just try it. At least when it comes to output, you should be sure. Other filters can then be tried out. First of all, the output must be clearly defined. I would click top line only 24 bits, middle line only 88 kHz, bottom line 192 kHz. Is that at least correct? No more ticks for the other options. Only this 3rd would mean:

CD - 16/44 kHz = 24/88 kHz
Hires 24/44 kHz = 24/88 kHz
Hires 24/48 = 24/192. Or
HIRES 24/96 (WHATEVER) = 24/192 KHZ
HIRES 24/176 (CANNOT PLAY MY DAC) = but because Upsampling= 24/192 kHz.

Then at least I have set the correct output. Then I could try it with other filters. Is my information correct now?

No I am not. But I can say for sure that it doesn’t do everything right. My point was only that resampling was predictable.

As they should. Squeeze and C-3PO are free software options. One tends to get what they pay for in this hobby, which is why I suggested using one of the paid apps if one expects richer capabilities.

Ok then you should ignore what Mark and I recommend about auto rate family if your DAC can’t play !76.4.

Just check only the boxes that align with what your DAC supports in the section that follows. This is showing what my DAC supports.

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Thanks for the advice Mark - I will make the adjustment as you suggest and let you know how it goes.

HAve been trying C-3PO with the advised settings to upsample mymusic to a maximum of 176k or 192k, as this is the max my dac can cope with. The results were not good with some cracking in the signal which I do not get with C-3PO disabled.

As a test I then adjusted Roon to upsample Qubuz with Squeeze player and was actually pretty impressed. The sound of Roon Server with FLAC compression disabled and upsampling enabled appropriately was almost as open as Squeeze server and player. So unless I am into a higly critical music session I am now using Roon server and Squeeze player and enjoying Roons brilliant interface.

Would be interested in others opinions?


So I’ve been listening to C-3PO for a few weeks now. I like it better with C-3PO. Although I have no idea what it does with the digital files. With activated C-3PO:

  • Music much quieter.
  • Quieter.
  • Warmer.
  • Bass is softer, less present.
  • Dissolved/Fanned.
  • Less stressful.
  • More long-term use when listening.
  • Even with a connected network (without switch, router directly) the music is pleasant. - Without a network connection, the music calms down again, seems fuller and more relaxed.
  • I don’t know if everything I hear when C-3PO activates is correct.

Without C-3PO:

  • Music seems more direct.
  • More honest and natural.
  • A bit louder.
  • Again a little more stressful when listening for a long time.
  • Bass much more present, more punch.
  • Seems to be the right choice. Still, I appreciate C-3PO very much. Listed below are my current settings for C-3PO. Every tick you set is audible, and therefore more confusing.

As an example: In the series of WAV, enable stdin i.e. Qobuz, when activated, the music is much quieter, but also pleasant. If the box is not checked/activated, the music is a little louder and fuller again. I have no idea what is correct?

So my general suggestions for Squeeze and C-3PO and their development and and and are:

  • I have no problem with the software being charged (for customers who want more without switching to HQ Player etc.).
    As an option as an example.
  • When using Squeeze, the CPU load is zero. Which already means that the software does a lot of things right.
  • Explanation (just at C-3PO) in German. Make it more self-explanatory. Based on examples.
  • The software can be as expensive as Roon annually. But the issue must be taken seriously.
  • The C-3PO function must not add to the server load.
  • Well, Squeeze is enough for me to listen to music with it, I really don’t need a Roon, only the app needs to be significantly better, especially when used with C-3PO. So I would pay for that too. I want a hassle free, great sounding app.
  • Then I would develop Squeeze as an app and not as a web server. I still have trouble connecting directly. Web server, clear cache problems. Everything annoying. No pleasure on it. Each web server is different, different problems (Apple, Android…). For DACs without display information, I need to get more info using C-3PO. What resolution is output. Actual - current - comparison. What do you think about this or antipodes to my proposal?

Is C-3PO being worked on? Will it be improved? Otherwise I don’t need to bother with it anymore…?

Addendum: I also mentioned that my DAC Merason DAC-1 MK2 cannot process 176 kHz synchronously. With my specified C-3PO settings, can I hear CD ripping? If my settings in the C-3PO are correct, my 44khz/16bit will be converted to 176khz. I can hear the upsampling?! But why? My DAC can’t do 176 kHz! If I disable C-3PO and play 176kHz natively, it distorts. That would fit that my DAC can’t process it. But why can I hear the upsampling at 176khz? Or what does C-3PO output to my DAC? Therefore, one needs more information about the function and its output.


  • Only listen to WAV.
  • No FLAC.
  • No streaming.

In addition: Heard today with these settings. Worked too. Recently received a distorted signal with the settings. Now it even sounds almost perfect with my 24/192khz DAC. I have no idea what C-3PO is doing there. It is also absolutely incomprehensible to me that such an immature function is created and not blocked again immediately, since there is no function. Please, dear manufacturer, don’t just pump the money into upgrades, but also into the software. In working software. And don’t burden customers with software that doesn’t work. We buy expensive hi-fi equipment to have peace of mind, not to have problems with it. Squeeze and C-3PO must have an approximate automatic function. As an example, enter the maximum sampling rate of the current DAC. And the software adapts to it. Then menus open up where you can try out additional filters. But everything stays clear. And not such a cramp as you currently have in front of you. I’m happy to pay for it too. If the topic is not taken seriously, the K50 is gone. I have neither the desire nor the time for such a thing. Squeeze and C-3PO are way too technical in the settings. 80% here in the forum want to listen to music and not mess with settings. Or make your own player app. Roon is certainly also technical and confusing here and there. You would only have to deal with one piece of software and this increases your basic knowledge.

C-3PO is an optional, free plugin developed initially by a third party (not the developers of Logitech Media Server aka Squeeze). You can read its history here: