Can anyone here give me an overview of the audible sound signatures that each lossy format has? What are their distortion signatures? Does one lean toward the slow side( transients not so sharp with fuzz around it) and the other toward the more defined sounding side(seemingly sharp because some data is lost around the transient) Something like that... For mp3, itunes AAC, Ogg, WMA, or whatever others that exist.

I'll start with my impressions from some of the posts here. Maybe someone can correct me.
-MP3 sounds blurry with high frequencies with problem samples
-Ogg has seemingly better definition because its distortion makes transients make its sound seem sharper than the original

What Else??? What about AAC?

And What Bitrates are their sweet spots? best sound/filesize compromise like VBR NEW V=2 for LAME 3.97 mp3 for example

Vorbis has something described as HF boost/noise/coarseness.
WMA usually suffers from metallic sound.
AAC and MP3 are very close IMO.

But these "signature" tend to disappear with high bitrate encoding (im my opinion).

At low bitrates all TC codecs and subband have similar artifatcs. These are distosions or even new sounds not present in the original. Some examples are: ringing, warbling, dropouts, knocking, dull 'lifeless', metallic, noise / coarsness. No audio equipment can produce these - they seem exclusive to lossy encoding.

With hybrid lossy like wavpack and optimfrog DS, there can be a difference of background hiss or noise around instruments but definately no 'artifacts'. Audio equipment might also produce similar noise e.g - tape, speakers, amp hiss.

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You will also find that many artifacts are much less format specific than one would think.

Some encoders (ogg for example) narrow the stereo image at low bitrates. Mp3 has trouble with frequencies >16kHz, but that is "by design". Throwing enough bits at it will cure the problem (in case you don't run out of bits when you hit the 320k barrier). What type of artifacting you will get with mp3, varies greatly with the encoder. Ogg could usually be picked out by listening for added hiss, but that has been pretty much fixed with the aotuv tunings.

Sweet spots really depend on what you are aiming at. For near perfection I guess you could say: mpc q5, ogg (aotuv) q5 or q6, mp3 (lame) aps, but ymmv.

I have little experience with either wma and aac.

Oh at what bitrate does itunes AAC attain transparency comparable to LAME 3.97b Preset fast standard for example? Can you give me a link to these comparisons if you know any

Oh, Is it just me or does nero 128 aac sound especially bad on winamp compared to playing it on foobar? All other filetypes sound better with foobar but aac sounded way better in foobar. I havent tested the higher bitrate aacs yet though. weird...