I know I'm definitely not imagining this. Since I switched over to KDE4/Amarok 2 from KDE3.5/Amarok 1.4 the sound quality has deteriorated.

I used to use Amarok 1.4 with xine output, going via pulseaudio to a USB sound card and into my Hi-Fi setup. Now I use Amarok 2.0.2 going into Phonon using a xine backend into Pulseaudio into a USB sound card and into my Hi-Fi setup. I've been using it a few days. The new setup is noticeably worse, quality-wise, than the old one. it's not a huge difference, but to my musician's ear it's noticeable and, frankly, not very nice.

Of course, to complicate matters, I've also switched distros in the process.

So, first question - does Phonon have any affect whatsoever? Intuition tells me it ought not to, but its an extra link in the chain so it's got to be the first suspect. (PLEASE don't let it be Phonon or I'll have to start using GNOME... )

Second question, is there any reason why a xine backend from one distro might sound worse than a xine backend from another? Bearing in mind the old distro was using kde3 of course.

Oh it's too complicated. I'll never upgrade again....

That could be a Pulseaudio problem. Why do you use Pulseaudio on KDE? You don't need that, Phonon+Xine can handle sound fine enough.

Well:
Pulseaudio allows me to pump my music to any room in the house. Or all rooms simultaneously. Phonon does not.
Pulseaudio allows me to play music from my laptop and have it come out through my Hi-Fi speakers without (visible) wires*. Phonon does not.
etc..
Pulseaudio is marvellous. Fortunately it can be used as a backend for Phonon (via xine) or I would be using Gnome... and I hate Gnome

..anyway..

This looks to be a Kubuntu problem. I've done a sound comparison between Kubuntu and Mandriva (which is what I used to use) playing the same MP3. Mandriva simply sounds better. I reckon it might be something to do with the MP3 codec they are using, not sure, anyhow it doesn't look like an Amarok issue. It has helped me decide which distro to use though

* on Mandriva it does. It's broken on Kubuntu...

Personally, I have recently bought golden Ethernet cables. You wouldn't believe how much this improved audio quality.

It's quite amazing


PS:
We plan to sell a special "Amarok Cable" (TM) in our shop soon. They won't be quite cheap, but a true audiophile won't regret buying them. Stay tuned!

You can tease all you like. 

These MP3 are MP3s of me playing with my band, so I know what they should sound like. I'm playing them back on reference studio gear, so it picks up small differences. There are differences between MP3 codecs that are noticeable when you know what you're expecting to hear. My reason for posting this here was that I was concerned about how Amarok handles MP3 data - does it pass it directly via phonon to the backend (eg Xine) or does it do some processing of its own first? Or does Phonon do any processing of it?

FatGerman wrote:You can tease all you like. 

These MP3 are MP3s of me playing with my band, so I know what they should sound like. I'm playing them back on reference studio gear, so it picks up small differences. There are differences between MP3 codecs that are noticeable when you know what you're expecting to hear. My reason for posting this here was that I was concerned about how Amarok handles MP3 data - does it pass it directly via phonon to the backend (eg Xine) or does it do some processing of its own first? Or does Phonon do any processing of it?

Ok, a more serious answer:

Amarok is masterful in the way it delegates all serious "number crunching" to external libraries. The application itself basically just tells Phonon: "Play this URL, ****!"

Interestingly, Amarok itself doesn't even know or care about the format it's playing. It's all abstracted. And Phonon itself is an abstraction layer, and delegates the work to xine, GStreamer, QuickTime, e.g., which then again delegate the work to other libraries (FFmpeg, etc).

So you see, we're really the wrong people to ask about such things. We provide the glue that combines all these little components into a useful product, but we don't have much influence (or knowledge) on the things that are done in the background. You would have to approach the Phonon/xine/etc developers for this.

Thanks Mark (I did appreciate your first answer too ).

I kind of expected that was the case, just wanted to make sure I understood it. Xine uses various plugins, which can be built with various options. My guess is that Kubuntu have erred on the side of lower CPU usage (or better performance, depending on how you look at it).

Anyway, I'd like to make clear that these differences are very minor, probably only bothersome to a fussy old muso like me. (Hell, I don't even use MP3 if the bitrate is less than 320Kbit). Music is the main purpose for my computer and Amarok is the core of it. So to learn that the quality is all in the codecs is very heartening (sounds like good design to me). Thanks.

Perhaps your soundcard is running at the default samplerate 48000KHz and pulseaudio uses a bad resample method to resample the 44100CD music up. You can change this in /etc/pulse/daemon.pa . Search for something like resample-method= and insert "src-sinc-medium-quality" this for example or even src-sinc-best-quality (very cpu intensive).

greets