Having the same issue here.
LGM for 1.6.4 won't download any resources but switching back to 1.5.2 it does without any issues.
Vanilla won't either unless it is set to 1.5.2. Setting it back to 1.6.4 or 1.7.2 after it downloaded the resource files it won't use them and the game remains mute.
Vanilla MC:
console for 1.5.2 - works
Starting up SoundSystem...
Initializing LWJGL OpenAL
(The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[LWJGL] getPathFromClassLoader: searching for: OpenAL32
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: sun.misc.Launcher$AppClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.net.URLClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.security.SecureClassLoader.findLibrary(java.lang.String)
[LWJGL] getPathFromClassLoader: searching for: lwjgl
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: sun.misc.Launcher$AppClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.net.URLClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.security.SecureClassLoader.findLibrary(java.lang.String)
[LWJGL] getPathFromClassLoader: searching for: lwjgl
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: sun.misc.Launcher$AppClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.net.URLClassLoader.findLibrary(java.lang.String)
[LWJGL] Failed to locate findLibrary method: java.lang.NoSuchMethodException: java.security.SecureClassLoader.findLibrary(java.lang.String)
[LWJGL] Found 8 OpenAL paths
[LWJGL] Testing 'C:\Users\Rabbit\AppData\Roaming\.technic\modpacks\vanilla\bin\natives\OpenAL64.dll'
[LWJGL] Found OpenAL at 'C:\Users\Rabbit\AppData\Roaming\.technic\modpacks\vanilla\bin\natives\OpenAL64.dll'
OpenAL initialized.
console for 1.6.4 - doesn't
2013-12-18 23:23:45 [CLIENT] [iNFO] LWJGL Version: 2.9.0
javax.imageio.IIOException: Can't read input file!
at javax.imageio.ImageIO.read(Unknown Source)
at atv.a(SourceFile:418)
at atv.O(SourceFile:274)
at atv.d(SourceFile:599)
at net.minecraft.client.main.Main.main(SourceFile:101)
2013-12-18 23:23:45 [CLIENT] [iNFO] Reloading ResourceManager: Default
Starting up SoundSystem...
Initializing LWJGL OpenAL
(The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
OpenAL initialized.
console for 1.7.2 - doesn't either
[23:32:43] [Client thread/INFO]: LWJGL Version: 2.9.0
[23:32:43] [Client thread/ERROR]: Couldn't set icon
javax.imageio.IIOException: Can't read input file!
at javax.imageio.ImageIO.read(Unknown Source) ~[?:1.7.0_45]
at azd.a(SourceFile:500) ~[minecraft.jar:?]
at azd.Z(SourceFile:340) [minecraft.jar:?]
at azd.e(SourceFile:689) [minecraft.jar:?]
at net.minecraft.client.main.Main.main(SourceFile:103) [minecraft.jar:?]
[23:32:43] [Client thread/INFO]: Reloading ResourceManager: Default Starting up SoundSystem...
Initializing LWJGL OpenAL
(The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
OpenAL initialized.
[23:26:22] [Client thread/INFO]: Created: 512x256 textures/blocks-atlas
[23:26:22] [Client thread/INFO]: Created: 256x256 textures/items-atlas
[23:26:22] [sound Library Loader/INFO]: Sound engine started
[23:26:27] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:music.menu
[23:26:45] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:music.menu
[23:27:01] [Client thread/WARN]: Unable to play unknown soundEvent: minecraft:music.menu
Is LWJGL causing the issue?
The default MC launcher is using 2.9.1:
[23:29:00 INFO]: Client> [23:29:00] [Client thread/INFO]: LWJGL Version: 2.9.1
[23:29:00 INFO]: Client> [23:29:00] [Client thread/INFO]: Reloading ResourceManager: Default
[23:29:00 INFO]: Client>
[23:29:00 INFO]: Client> Starting up SoundSystem...
[23:29:00 INFO]: Client> Initializing LWJGL OpenAL
[23:29:00 INFO]: Client> (The LWJGL binding of OpenAL. For more information, see http://www.lwjgl.org)
[23:29:00 INFO]: Client> OpenAL initialized.
[23:29:01 INFO]: Client>
[23:29:01 INFO]: Client> [23:29:01] [sound Library Loader/INFO]: Sound engine started
Copying the 2.9.1 version inside the library doesn't work, deleting 2.9.0 and it will just re-download it, editing the version.json file to disallow 2.9.0 also doesn't work - re-downloading.
Thought I'm not even sure that the older version is the actual issue.