I created a little codec-test only for personal use in the last week and noticed, that NeroAAC with VBR-Modes adds a few artifacts in quiet passages and before/after drum kicks and bass. These artifacts doesn't occur with CBR.
I've also noticed a real crappy sound with FAAC (till q500!). Level fluctuations, clipping and a noisy bass.

Please test it, if you want.

Here is a sample from a song I've written and recorded last year (27sec, compressed with Monkey Audio 3.99).

You should encode it twice:
1st as it is
2nd with decreased volume for about 2dB to avoid clipping (cos its normalized to 0dB)

EDIT:
Sorry, i tried to add the sample as attachment but it doesn't seem to work.
What's going wrong? The filesize is 2.28MB. It's too large?

EDIT on August, the 5th:
The File is now 20 sec. long and here is the link to the right post:
http://www.hydrogenaudio.org/forums/index....ndpost&p=232014

Does it give any error when you try to upload? Uploading a 2.28MB file can take a long time with modem.
The size limit is 9MB so it's not that.

No, there's no error message.
I searched the sample, clicked on "Add This Attachment", it began to load for about 15 minutes, but after it there's no attachment added to the post.
Where has the sample gone?

I can't see what's wrong, the permissions are set correctly. Can you try uploading a smaller and different file (not APE)?

I tried it a fifth time.
Okay, now i'll try to attach the encoded ones

EDIT:
Ok, the smaller files are online
But, how can I now make the "Source" available?

Btw. all the files were encoded via foobar2000.
For FAAC i set q106

As you can hear, the FAAC-File sounds something strange...
The Nero vbr-File has some quiet smacking or popping noises (like echoes) around the bass drum and the bass at the beginning. I've noticed, they are not as loud as in the whole encoded Track.
The Nero cbr-File sounds as good as expected with 128kbps

Hmm.. We seem to have a problem with files over 2097152 bytes for some reason even though 9MB is set to a limit from forum software.
I'm on modem at the moment so I have limited possibilities to start checking this out right now.
If you could make the original problem section smaller than 2MB it would be great.
Original is definitely needed in order to have any use of the sample.
Thanks.

Ok, I'll try it with the same sample, cutted down to 20 sec. But the shorter the file the less and undertoned artifacts were produced by NeroAAC VBR...

Please remember:
You should encode it twice:
1st as it is
2nd with decreased volume for about 2dB to avoid clipping (cos its normalized to 0dB)

You should know, that I noticed these artifacts in all NeroAAC VBR-Modes except "Transcoding". But not in CBR-Mode with assimilable bitrate.