Thanks for this tip. I actually thought about this loader issue. But I didn't find the right place to change it... Now I found it and it's working.
I added a new loader AssetLoadBySoundLoader.as, which organizes the sound load. The only problem is, that the loaderContext should be of type SoundLoaderContext. If I change it, it cannot implement IAssetLoader... So I just set this parameter to null (loader.load( url, null)).
I'll send the files to you, so you can add them to the package, if you want.

Hi Philip,
Thanks for this great utility. I just started a big project with a lot of asset-loading stuff and it's really amazing, how easily and clearly I can manage these loading operations with your Loadup utility. Thanks to Tek (http://www.tekool.net), I use it in a pure actionscript project.
But now I came to a problem. I would like to use this utility to load sound assets (.mp3). In fact, your utility does load such assets. At least I think it does. But I don't know how to cast this asset properly to a sound object.
I wrote an AssetOfTypeFlashAudio class, extending the AssetBase class and implementing IAsset with a getter method, that returns a Sound object. Finally I added a AUDIO_ASSET_TYPE const to the Loadup class.

When the asset is loaded now, it's returned by the AssetOfTypeFlashAudio class. Then I try to cast it with var sound:Sound = audioAssetClass.sound . This works, too. But as soon as I try to play it (sound.play) it throws an error #1009: Cannot access a property or method of a null object reference.

Has anyone already used this utility to load sound assets?

Thank you for your time.