Howdy,

I have an Alpine CDA-9887 with an iPod connected via "Full Speed" USB.

According to a rep at Alpine, the iPod sends a digital signal over USB to the deck, and then the deck's 24bit Burr-Brown DACs D/A it.

According to Apple, Apple Lossless, which is part of the MP4 AAC-LC spec, should be identical to the digital source.

So here's the weird thing.

When I A/B the same song from a retail CD and the Lossless file that was ripped from that very CD, there is a noticeable difference. I've had other people listen and they agree. The CD sounds cleaner and more defined.

So, my question is this. (Bracing for guesses and conjecture and opinions)

Is there a difference because:

1- Apple Lossless isn't really lossless.
2- The iPod decodes all audio into PCM, badly, and sends that.
3- Someone is lying and the iPod's crappy DAC is doing the D/A and sending analogue.
4- I'm hearing things

Thanks!

-Drunkenrobot

 

here is a good read for you


http://www.audiokarma.org/forums/sho...d.php?t=137477

 

So, there is a possibility that the ECC ripper in iTunes introduced artifacts into the Lossless file... I will re-rip the CD with EAC and transcode it to Apple Lossless and have another listen. Maybe that's the issue. Thanks!

 

...and unless you do a proper abx test with the two, you can't be sure you're actually hearing a difference, or if it's psychoacoustics playing tricks...same old story. Anyway, if you feel one sounds better, then by all means use what you like better...if your mind tells you one sounds better, who cares what anyone else says!

 

Yeah. That's why I was wondering if I was hearing things! :-)

I wish it wasn't so hard to do a double blind.

I also wish I could find out if the iPod was sending PCM or straight encoded data.

Is the deck decoding the audio to PCM for the DAC or is the iPod decoding PCM for the DAC?

 

Did you do apple lossless without correction?

 

I ripped a brand new, just out of the wrapper CD with iTunes, with ECC (error correction) turned on, and encoded it into Apple Lossless.

 

I REALIZED YOU HAVE A 9887 WITH A 422i CABLE..THAT SYSTEM WAS ANALOG AS FAR AS I RECALL, IT OFFERED HIGH SPEED FILE SEARCH AND DOWNLOAD, BUT THE OUTPUT WAS ANALOG. THE NEW DECKS USING THE 440i CABLE LIKE THE CDA 117 ARE PURE DIGITAL, SO THE DIFFERENCE YOU HEAR IS PROBABLY CORRECT.
check this thread out for more info specific to the high speed cable:

http://www.diymobileaudio.com/forum/member-reviews-product-comparisons/30884-alpine-cda-9887-full-speed-connection-analog-digital.html

 

Hmm. Good point. It may be just a level thing. The cd is certainly much much louder, and I have to turn the sub down quite a bit, relatively. I'll try ripping the test track again with EAC and re-encode it and see how it comes out.

 

I also wonder if the deck or the iPod does the decoding to PCM. The deck may be using the Burr-Brown to do the D/A, but which one is doing the decoding to PCM?