Soundcheck and Db level of songs

Soundcheck seems to be non-functional in iTunes 6.02, or at least there are bugs.

I play music for a living as a DJ using iTunes.
I have found disabling the soundcheck gives a better quality of sound. Form the other posts, it seems MP3's have a raised db level over AAC's, so soundcheck is supposed to level out the db's no matter the format. Apparently it over compensates. I was experiencing muddy sound from my self-amplified speakers with soundcheck on. I have shut it off until I can hear it actually working as advertised.

I've also noticed a problem recently with soundcheck.
I'm running itunes 6.04, but can't tell you when the
problem started.
The results are VERY inconsistant. Sometimes a song will
be listed with a negative playback Volume but activating soundcheck makes it play louder! Some times the other way around. And sometimes it seems to get it right.

I was thinking about trying iVolume, but, if it doesn't work in 6.02 (and presumably later) then that is not very appealing either. . .

I think perhaps part of my problem in my library has been built up over many years, using many different versions of iTunes.

Is there a way to force iTunes to recalculate the volume of all songs? (If so, I'd feel more comfortable testing
iVolume to see if it did a better job)

The idea of soundcheck is to simply make quiet songs louder and loud songs quieter, thereby making all of your tracks the same volume. I am guessing the IVolume does exactly the same thing, though having not used it I do not know. I personally use soundcheck all the time on my iPod. This is because some CDs are just intrinsically louder than others, meaning that without it on, I may turn up the volume for a quiet song, which is then followed by a very loud song - resulting in a very painful experience!

How long did it take to process your 6300 song library?

Is this program iVolume available for the Windows version of iTunes? If so, where can I download / buy it?

Thanks,
WIllem

Another question. I've been thinking of using an external audio editor such as Cool Edit, to set all my songs at the same Db setting. Cool Edit has a batch processing option, so that would make it easy to do this.

Now I wonder, what would be the correct DB setting? Should I level out all songs at 0 Db? Or would +3 DB (or even more) be better? It seems to me that cd's nowadays get recorded louder than some years ago. Therefore, all older cd's sound softer.

Anyone has any tips on this?

Thanks,
WIllem

For Windows, there is no better solution than foobar2000. It has full ReplayGain support, which is superior to Sound Check. See here for technical details.

Likewise, for OS X, there is also no better solution than ReplayGain. For MP3s and unprotected AACs, the most functional solution is MacMP3Gain. It is also free. It's important to mention that with ReplayGain, you can make adjustments to files at the album (audiophile) and track (radio) level. If your library consists of complete albums, then album gain is the way to go, as it will preserve the subtleties of the album and the listening experience will be as it was intended.