Every Computer, MP3 player, iPod, iPhone and music device out there has a small chip inside that takes a digital file and converts it to analog audio. Depending on the DAC design, the chip will smooth out the rough spots, fill in the digital holes and balance the volume. Just like computers CPU, the better designed the DAC chip is, the better the sound quality. There is a huge difference in abilities & quality between a DAC in a $5.99 CD player from Walmart and the DAC in a $1000 sound system from a high end audio store.
In a perfect world your music looks like this and sounds great
Here's a representation of the output from a normal DAC
Notice how it approximates the curve with a stair-step function? That's not the best sound and to a discerning ear it can sound awful.
I won't bother you with all the technical details of what makes a good DAC, just know that there is a balance of bit rate, sample rate, filters, clock-rate as well as production costs.
Some audiophiles say only an old fashioned tube will give you the "warmth" of live audio. Some argue that upsampled bit-rate is the key. There are a ton of articles and arguments out there on what makes a good DAC and if it's worth the cost. I'll list some links at the bottom of the post if you are interested. For now, just know that as expensive as the new MacPro is, one item that isn't top tier is the built in DAC.
I did some digging and found out the MacPro probably uses a chip based on the Cirrus Logic CS4207. Not a bad chip but there are better.
So after all this technical talk be aware that there are a lot of DAC choices out there. DACs are built by every major electronics firm and a lot of independents as well. Look around, you'll find them. After months of looking I finally decided on a quality DAC built by Schiit Audio. Yeah, go ahead and say that name out loud and laugh, they laugh at their name as well.
"Yes, that is our name. Shih-tah. It's a proud German name, host to a long line of audio engineers who slaved away in crumbling Teutonic fortresses as lightning lashed the dark lands outside, working to perfect the best amplification devices in the world...
Or, well, no. Yep, Schiit is our name, and it's pronounced, well, like "hey man, that's some really good Schiit!" And now that we have your attention..."
With my DAC I also purchased a pre-amp volume control and have never been happier. Here's a diagram of my audio setup:
The sound quality with the DAC & speakers is wonderful. Much better than the analog output directly from the Mac itself. If you are an audiophile or just someone interested in getting better sound out of your Mac, I highly recommend looking into a DAC.
- How DACs work
- Wikipedia DAC entry
- Cambridge Audio - What is a DAC
- How Stuff Works - DACs
- Reddit Audiophile
- Video - DAC explained by OGG Vorbis Codec Creator
- Music Quality Explained