Differences between iTunes and dBPowerAmp when ripping in Apple Lossless

iTunes use the Apple Lossless encoder built into QuickTime (the "real deal").
While dBpoweramp use a reverse engineered encoder. The dBpoweramp encoder is not perfect, as in that it have caused playback issues on iPods and it also do not support high-resolution content. Would not be surprised if there are file size differences as well.

I believe dBpoweramp uses the Nero encoder for ALAC. Personally, I could never tell any difference in SQ on Redbook material. High rez files is, indeed, another story

I would expect so. The ALAC encoder that dBpoweramp uses is lossless. So conversions should be lossless as well. The trick will be in figuring out how to get iTunes to re-encode the dBpoweramp ALAC files to iTunes ALAC files.

I'm not sure how to go about doing the conversion. I don't use iTunes so I'm not familiar with its exact workings. If iTunes won't convert the dBpoweramp ALAC files directly you would have to take a round-about way by doing something like first converting the files to WMA Lossless using dBpoweramp or something similar then having iTunes convert the WMA Lossless files to iTunes ALAC. iTunes for Windows will read WMA Lossless files.

I don't have much trust in the open source implementation of the ALAC encoder/decoder. It was created by reverse engineering without any benefit of even a technical specification from Apple. It is also limited to 16-bit files only. It can't guarantee perfect compatibility with Apple's ALAC encoder/decoder. It is not something I would trust my library to as a primary or archival format. The only thing I would consider using it for would be to transcode from another lossless format to be able to put lossless ALAC files on an iPod, and even there I wouldn't expect perfect compatibility.

I'd stick to itunes when encoding in ALAC. After all...they created it didn't they?

They own it, they control it, it has patents, they don't have anything technical about it public. It's a dead end, Apple only toy.

I found a couple of HydrogenAudio threads discussing the ALAC encoder used by dBpoweramp. Not a lot of detail there, but if there was some sort of loss of quality or other problems using the dBpoweramp encoder then HydrogenAudio would be all over it.

Non-Apple ALAC encoder
Apple Lossless Encoder, that does not require iTunes / QuickTime

Using the dBpoweramp ALAC encoder as an intermediary format should be perfectly fine. In that case the dBpoweramp ALAC encoding is short lived and serves a useful purpose.

My concern with using the dBpoweramp ALAC encoder would be for using it as your primary format long term or for archival storage. I wouldn't trust it long term and especially for archival storage. Everything was reverse engineered. You have to trust that they got it all right. If they did something just slightly different or slightly incorrect a future version of iTunes or some other tool in the future could corrupt the files. I just don't trust it. Apple isn't going to run compatibility tests against dBpoweramps ALAC implementation when doing QA on future versions of iTunes and ALAC. Third party tools that support ALAC are going to test against Apple's ALAC implementation and may completely ignore testing against dBpoweramp's ALAC implementation. (I do software QA, I don't have a lot of trust non-conforming software to continue to work or remain compatible)

In your case the dBpoweramp ALAC file is short lived. It soon gets converted to the iTunes ALAC format and is all good.

You could also experiment with using Windows Media Audio Lossless. dBpoweramp can save to WMA Lossless. iTunes can read WMA Lossless. It would be an option and is a format that would support 24-bit if you wanted to import 24-bit files. But for regular 16-bit CD audio the dBpoweramp ALAC encoder is probably easier to deal with.

Unless your CDs are scratched really bad, just use itunes to rip. There's not much of a difference. Turn on error correction and you're set.

I was playing around with the latest release of CUETools (version 2.0.3) this morning and see that it now does ALAC encoding (M4A). You could use CUETools instead of dBpoweramp to convert the files to ALAC before importing them to iTunes. The advantage to using CUETools is that it can let you know if the CD has hidden audio in the pregap area for track 01. CUETools will extract the track 01 pregap audio to a file named "(HTOA)" which stands for Hidden Track One Audio. You can then check to see if "(HTOA)" is just silence or contains useful audio.

Download CUETools 2.0.3 from HydrogenAudio: CUETools download
It has not installer. Extract the files and put the folder in your "Program Files" directory and manually create a shortcut to be able to launch CUETools.exe

You'll also need to download ffmpeg.exe to be able to create M4A (ALAC) files. Get ffmpeg.exe from MPlayer. Download the file "FFmpeg-svn-19159.7z". Extract the files (7z is 7zip file similar to a regular ZIP archive). Copy the FFMPEG.EXE file to the directory where you installed CUETools.

CUETools should now be able to do M4A (ALAC) encoding.
For Action select "Encode and verify"
For Audio Output select Lossless and m4a
For CUE Style select Tracks

For ripping you would use EAC to create a CUE file
The use CUETools to split the CUE file image into individual tracks and encode those tracks as m4a
Import the m4a into iTunes and use iTunes to convert the m4a files to proper ALAC files

That should work. I haven't tried the actual import and conversion using iTunes to be sure.

CUETools is a bit complex and does force you to learn a little more than you probably wanted to know about CUE files and things like the difference between "Gaps Appended" and "Gaps Prepended". Not the most noob friendly app. I like it though. Quite handy.

WMA 24 bit files get converted to 16 bit by Itunes when encoding to ALAC. AIFF is the best intermediate codec.. keeps tags, and retains 24 bit when converted to ALAC