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View Full Version : Sound quality: CD player vs. CD drive vs. Mac hard drive




Naimfan
Oct 1, 2007, 07:09 PM
I've always been a huge fan of music--probably inevitable when your grandfather teaches piano and your grandmother is one of the original Rockettes. (Yes, really.) Since I can't play, I've always loved listening to music, and have liked hifi gear, getting into what most people would probably call insanity--having a record player that would now retail for $10K, etc. So iTunes et al have been enormously interesting to me.

I just got an Airport Express so I can stream radio stations from my iMac to my hifi, and have experimented with the sound quality coming from a variety of sources--my CD player (a Linn Mimik), playing CDs in my iMac, and a couple of different bit rates in iTunes; with the latter two being streamed to the Airport Express and then to the hifi rig.

Short form: The CD player directly into the preamplifier is the best sounding, and it is my sad duty to say it is by a sizable margin. As in, anyone could hear it. (It is actually second best--my turntable kills it, but that's another thread!) Second, surprisingly to me, was the iMac playing the CD directly--it is better than playing the identical track from the hard drive (encoded with Apple lossless). Third was playing music from the hard drive after it was ripped using Apple lossless (which is the best sounding encoder I've tried).

I'm surprised because one of the biggest bugaboos with digital sound is jitter, which playing from the hard drive should eliminate. Granted, the Mimik is designed in part to minimize jitter, but still......

I think the biggest reason is that the D/A conversion in the iMac is nowhere near as good as that of the Mimik, and then streaming it doesn't help, nor does running it through a cheap mini to twin RCA cable (although substituting RCA cables shows them to not be a huge factor). So perhaps I should get a better D/A converter to plug the streamed music into, and let that handle D/A duties as opposed to the iMac.

Briefly, the Mimik is much more authoritative--bass goes deeper and with more power and control, the music is much more "in-tune", much clearer, and easier to follow. As you move to the iMac playing the CD directly, the music compresses--you can hear the dynamic range being squashed, the image and soundstage collapse, and it's much harder to follow the "tune." Music also loses a great deal of it's color and dynamics.

Anyway, I've always wondered if anyone else here has done anything similar, and if there are any other audiophiles here. Now, back to converting my 5000 LPs....... :eek:



/V\acpower
Oct 31, 2007, 01:41 AM
I'm not the biggest audiofile (however I can ear difference, I'm not just into high quality sound systems)

What I know.

The iMac have an optical audio port, and technically, it is the best way to connect your iMac to a sound system. Any Wireless solution will obviously give you less quality than any direct input to the sound system.

However, as for the CD vs Harddrive. Keep in mind that a CD is a stricty digital format. A CD is simply data that is encoded in .WAV (technically it's not exact, but the Audio CD filetype "Redbook" have the audio data encoded in the same way as a .wav). Any music CD player is just reading data from the disc. There is no direct audio output from the CD to the sound system. The source of the music file (.wav) doesn't have any influence on the quality output. It could come from a CD, a Harddrive or even a USBStick, it wouldn't make any difference.

The two big difference in your example is :

-The Airport Express (wireless)
-iTunes and encoding

Comparing Wireless to direct input on a high quality sound system is simply not fair. That's for Airport Express.

However, the major issue is software and encoding. Technically Apple lossless is not supposed to lose any "music information". Honestly I don't know if it's really a true lossless conversion. However, I know that iTunes is not the best encoding software to convert Audio CD to any computer files. It do the job for iPods and every standard consumer devices, however, when searching for the ultimate sound, iTunes encoder is not the best.

There is other specialized encoders that are better at encoding. (I don't exactly their names) and you should get one to encode your files.

If you want to play them in iTunes, you have to stick with Apple lossless or AIFF ( close to .wav, but bigger than any lossless solution) or WAV. If you have lots of harddrive space you could use a software to encode your CD into .WAV, and with a direct input from your iMac (preferably optical), you should get the same result as a CD in the sound system.

But It think that encoding in Apple Lossless with the good software should get you to the exact same result since the lossless is by definition a compression algorythm that can be decompress to the exact same data as the original.

CanadaRAM
Oct 31, 2007, 01:56 AM
Nope, it's a whole lot simpler than that.

The Linn has +/- $300 D/A converter circuits in it.

The Airport Express and the Mac have +/- $0.30 D/A converter circiuits in them.

The reason the optical out from the Mac is superior is that you are bypassing the cheap converters, and relying on your receiver or speaker system's D/A decoding.

QuarterSwede
Oct 31, 2007, 02:05 AM
Any Wireless solution will obviously give you less quality than any direct input to the sound system.
Not so with an Airport Express if your using the optical out on it. It would be straight from your hard drive > wireless router > airport express > optical out > whatever high end receiver you have. It stays digital and unchanged until the DAC in the receiver converts it to an audio signal.

Assuming your CD is playing on the same receiver your Airport Express is: If you're hearing any difference between a CD and what's coming out through the optical out on an Airport Express, it's in your head. This is because it's exactly the same bits and bytes going through the same DAC and speakers.

CD > optical out = Hard drive > optical out

Killyp
Oct 31, 2007, 05:43 AM
Not so with an Airport Express if your using the optical out on it. It would be straight from your hard drive > wireless router > airport express > optical out > whatever high end receiver you have. It stays digital and unchanged until the DAC in the receiver converts it to an audio signal.

Assuming your CD is playing on the same receiver your Airport Express is: If you're hearing any difference between a CD and what's coming out through the optical out on an Airport Express, it's in your head. This is because it's exactly the same bits and bytes going through the same DAC and speakers.

CD > optical out = Hard drive > optical out

Exactly. In fact, to test this, they checksummed the result between the output from the back of a hi-end CD player digital output and the optical out on an AirPort express on a hi-fi forum I'm a member of, and the result was that there is no digital information lost at all when using the AirPort express. The weak chain was the DAC, which made it sound 'wooden' and slightly dull, limited bass extension and detail.

Sticking a decent DAC on the AirPort express will make it sound much better, and you could technically end up with a better sound than the CD player.

CMD is me
Nov 13, 2007, 09:48 AM
Recently I put a bought CD in the home stereo (Luxman + Energy towers) and it was like I've never hear music before. Everything I listen to is over compressed -- especially Sat radio. I've tried different forms of compression with my CDs and the result is all similar. Lossless is great, but I'd need to invest in some mega HDs!

Cehtna
May 10, 2009, 09:13 AM
I just got an Airport Express so I can stream radio stations from my iMac to my hifi, and have experimented with the sound quality coming from a variety of sources--my CD player (a Linn Mimik), playing CDs in my iMac, and a couple of different bit rates in iTunes; with the latter two being streamed to the Airport Express and then to the hifi rig.


Yeah me too, can you please tell us with your results and conclusion?
What did you settle on then, what are you using today?
Did you use the optical output on your Airport Express?

Right now: .mp3 > MacBook > iTunes > AirPort Express > old Denon receiver (without optical in)

Looking to upgrade you se, and wondering:
Airport Express optical to surround receiver, or is
Airport Express jack to stereo amp just as good?