Conclusions and more info
The programs I like best for sound:
Winamp 2
For me winamp 2 is still the best player, with iTunes behind it since I found out about the Quicktime settings that it relies on. Winamp 2 comes closest to playback in a dedicated wav editor in which the file was made. Too bad that thiss app cannot play flac, although there may be plugins for this.
** Update august 2010: Winamp has many settings. Of much importance is the one where you choose your preferred soundcard but also very important is the waveout setting. You should avoid Windows soundmapper but can choose between Directsound and Wave out. Unlike in iTunes, Directsound sounds much softer and is altogether undynamic and uninspiring. In addition, Winamp 2 sounds liveliest if you avoid upsampling and/or filtering of any kind.
Mediamonkey and Media Jukebox
The choice between these comes down to taste. Mediamonkey plays almost to the same standard as winamp 2 but is on the one hand softer in the bass, with less attack and on the other hand it is softer in the high frequency, which is actually not such a bad thing because this makes it more friendly to bad recordings. Media Jukebox is a well-balanced sounding application that has a very nice interface and plays everything to a high standard. I guess you could call it neutral and it is an excellent alternative for Winamp but I kind of like the special fluidity of Mediamonkey. Even though you could call it less neutral.
Getting the most from Winamp 5:
I didn't like Winamp 5 before, due to its dynamic compression. Shame, because otherwise it's very well-behaved, having smoother highs than winamp 2. But it is way too rounded off and lacks dynamics and expressiveness. Please note: this observation was done with standard settings.
*** Update august 2010: I installed the latest version (5.58) and found no difference in sound quality. But after some more digging, I managed to find some settings that make a profound difference for the sound quality. If you set them as I will explain below, Winamp 5 will sound more similar to iTunes on Windows (again, with proper settings), which makes it an app that I can recommend after all.
1.) plugins - output - select your soundcard or device directly, don't use windows soundmapper, disable volume control.
2.) plugins - input - nullsoft module decoder - enable FIR interpolation (HQ) instead of Interpolation
3.) General prefs - Playback - disable 24bit playback
4.) General prefs - Playback - disable dither
5.) General prefs - Playback - eq tab - disable limiter
With these settings winamp 5 has finally lost its "compressed" quality. The feeling that the music was playing with the hand brake on is now all but gone. Everything sounds much faster and more dynamic while maintaining the smoother character Winamp 5 has over winamp 2, which may be drier but is also still more exciting to listen to. Winamp 5 now sounds mature and is an excellent choice if you like some smoothing of your music. Winamp 5 is the fullest sounding playback app of the bunch.
Getting the most from iTunes on Windows:
This one really is easily the worst program of the bunch. No doubt this has to do with conversion and compatibility with windows XP. On the Mac iTunes is actually excellent. But please note: this is with default settings.
* Update august 2010: Actually, iTunes for Windows turns out to rely on the settings made in Quicktime player. In there you can specify the bitrate and samplerate and make iTunes capable of playing high res files. If you specify 92kz and 24 bits iTunes will upsample (or downsample) all material to that bitrate. Upsampling does a nice job at adding a hint of air and more ease, at the expense of a bit of tightness. Very much a matter of taste. While you're at it, in QT settings you can also change the output from Directsound to safe mode (WaveOut only). Officially Directsound should be better but in this case "safe mode" sounds much fuller and livelier. You cannot however, choose a specific soundcard and therefore cannot bypass Windows' kmixer, unless you use a third party program and do some programming. I use the program "Virtual Cable" to make a direct connection between iTunes and my preferred soundcard. This bypasses all Windows-related mixing and conversion but doesn't bypass iTunes' filters, amongst which is the bitrate and samplerate setting done in Quicktime. But when used like this, all of a sudden, soundwise, iTunes comes in right next to my still slightly preferred Winamp 2! Done this way, iTunes has a nice relaxed feel, with excellent fluid highs and full, round bass. It doesn't have all the tightness and rhythm of Winamp 2 but iot becomes a matter of taste now, not so much a matter of absolute quality anymore. I am really glad that I found out about this because iTunes is operationally very pleasing to use.
On a side note: in Windows 7, iTunes has more or less the same features. Or lack thereof. In other words: in Windows 7 you still cannot choose your preferred soundcard in the QT settings.
Foobar
This program takes a special place. I personally don't like it but this is personal because this player is actually very accurate and also has options for upsampling and kernel streaming. For me its sound is a bit too controlled and too dry. Much like a digital sounding cd player. But there may be people out there that have less open and detailed playback systems that may tend to the dark of sluggish and on those systems Foobar may even be preferred.
Final Thoughts
I want to stress that the results published here are valid in my system. Surely their comparative and relative differences will still be true on other systems but please keep in mind that everything is very system dependent. But at least I think that I have made clear that there are indeed large differences to be heard amongst the various audio playback applications.
After the large audible differences that I found using the various playback applications and their settings, and their dependence and relative validity depending on the rest of the system and the consequent mess that this has created, I decided to undertake a second comparative test, this time using both Mac and PC as well as all currently popular playback applications and a handful of add ons for these applications. On top of this, I used not only my EMU 1212M soundcard but also USB solutions like M2Tech's HiFace EVo, Arcam rDAC and the very special Ayre QB-9 USB DAC. Using these components, I repeated all tests done above and with this report I will provide a clearer, more comparative overview. This turned out to become one of my most elaborate tests ever. For the result, look here: File formats and playback applications compared - part 4 - Mac versus PC
ALSO READ: