I just received my first DAC yesterday. I also have a MacBook Pro. There are too many devices hooked up to my USB ports so I decided to get a firewire one. I got the Echo Audiofire 2. When plugging in my headphones directly to the headphone out of the Audiofire, there was no undesirable noise.
Comparing the sound from the Audiofire to the onboard soundcard (Intel HD Audio), the sound was clearer with the Audiofire, but it wasn't that big of a difference like everyone hyped DACs to be. Maybe I was expecting too much. However, my music is more enjoyable with the Audiofire.
Here are some measurements and a review: Audiofire 4 review Russian translated to English. It looks like the numbers are pretty good. I decided on this one versus the others cause of the reputation for it's drivers. And it's true... the drivers are very stable and it worked with itunes and flash movies. Installation was a breeze.
After being a little underwhelmed by the DAC on my Audiofire, I've been kind of doubtful about all this hype on sound quality from forums. Like lossless files... I compared my ALAC files with AAC files downloaded from itunes. I can't tell the difference even though people claim lossless files make a world of a difference.
Photography forums are the same. People on there spend thousands of dollars on the newest DSLR and lenses. You really don't need that to take good pictures. My 35mm film Contax G2 kills a lot DSLRs in picture quality. Even my $80 35mm point-and-shoot Olympus Stylus Epic is better than some of them.
Anyways, that's just my rant after spending 3-4 weeks researching about audio equipment. When reading forums, it's very easy to get caught up in buying stuff that you might not need.
