Music from hard drive better than CD?

Marco, for someone who's learning you've got a pretty good grasp of this!

What you're talking about here is also known as jitter. Here are a few articles that explain what's going on:

http://www.soundonsound.com/sos/Apr03/articles/digitalclocking.asp

http://www.benchmarkmedia.com/appnotes-d/jittercu.html

Wow, quite a long thread here. Glad I wandered over from the other forums.

I've been fully hard-drive based for about a year. The system is based around an Apple iBook G4-1.1Ghz with just under a terabyte of firewire hard drives holding approx. 1500 CD's in Apple Lossless format. I tried the Airport Express spdif out, but in the end I preferred a USB extender cable running along the baseboards feeding an M-Audio Audiophile USB then into a Musical Fidelity A32.24 DAC.

The Airport Express didn't maintain digital sync which inserted a 2-3 second space every time you accessed a new track (nothing when playing sequentially). That's really the only reason I went the USB route.

Can it work? Absolutely!

Can it sound great? This setup replaced a Naim CDX2 with XPS2 (over $10k list price) and my wife and I both agree that the sound quality is just different, neither better nor worse than the Naim. That's saying something given the huge price difference.

Graham

Nick,

A few suggestions:

1. Set the buffer for the MBox to the highest setting. (why don't you report all of the settings back here and we can maybe see if something else is up)

2. Unsure which Wadia you're using, but what settings are available on it? Upsampling all the way to 192k on my MF DAC destroys the PRaT and makes everything overanalytical as well, so I leave it at 96k.

Graham

First, you're falling for the marketing that Digidesign wants you to. True, their high-end gear is used in pro studios around the world. Does this mean that their low-end gear sounds as good? (nope) The mbox is NOT used in pro studios around the world, as it's a prosumer device at best.

Second, the mbox has a horrible reputation amongst Mac musicians for driver issues (and being overpriced).

Third, every audio interface worth more than a hundred dollars has a driver configuration process. Nick, looks like it's time for you to RTFM :) If you want to use toys that come from the studio world, you should learn how to use them before knocking them.

At first it sounded to me like a jitter problem. Your DAC isn't correcting for it, so that's going to be the only difference between a cdp out and your mbox out, all other things equal.

Now, when you say that there is a difference through the mbox between music from the hard drive and a cd in the tray of the same computer then that points to a setting in itunes that somehow doesn't affect direct playback (which I didn't think existed). In the audio tab in iTunes Preferences do you have "Sound Enhancer" or "Sound Check" turned on? In the importing tab are you selecting "Use error correction"? Beyond that, the most important settings are going to be for the mbox.

Perhaps you should run Norton Utilities on your hard drive to see if there are any physical problems? I've done this test with a number of computers, several audio interfaces, multiple DAC's, and in studio and living room scenarios. They've always sounded equal to my ears (and barring any physical defects in your equipment) they should be. Technically, there are well-defined validity checks built in to hard drives so that things like this don't happen.

By the way, if a studio "pro" goes on the road to mix (quite a rare occurence as live and studio mixing are quite different animals) then they mostly take a part of their ProTools rig with them on the road and capture multitrack. These people are obsessive about sound, so stereo wouldn't be enough to capture what they'd be after. If it's just a matter of two channel, they'd just ask a roadie to pop in a DAT to capture the FOH mix and focus on the job at hand.

If they are doing it themselves on the cheap and don't want to move away from ProTools, they'd also more than likely use a rackmount interface like the Digi001 or Digi002 Rack instead of the mbox. Being on the road is a rough place and being tucked away in a rack means it will survive a tour while being on the desk means it is going to get destroyed.

Nick, I just want to make sure that you're not fooling yourself into thinking the mbox is any different than any of the other sub-$1000 interfaces out there.

Using error correction when extracting information from a CD is just an extra level of validation that you're getting a bit-accurate copy of the media. It takes longer, but worth it when you're looking for the best possible reproduction. You can think of it as a second scan of every ring, and you're right in thinking it has nothing to do with playback.

Apple Lossless Compression is bit-accurate and just involves a storage compression routine. Compression has gotten a bad rap from the audiophile community (sometimes for good reason) because of the inherent loss in mp3 and other compression schemes. When ALC tracks are played back, you get the same 16-bit 44.1 KHz signal that would be coming from a cd or wav/aiff file. Just like using winzip or stuffit to compress a Word document then uncompressing it later.

To address your question about toslink vs. coaxial: they both transmit the same spdif standard information so it's a matter of preference and what your equipment has. Some say that optical is more prone to jitter, but with jitter correction circuitry I'm sure you can see how any differences would be minimized to insignificant levels. A bit is a bit is a bit.

Two other commonly found digital audio transmission protocols are AES/EBU (which uses a balanced cable) and ADAT (which uses the exact same toslink fiber optic cable but has capacity for up to 8 audio channels).

Make sense?

Now to confuse matters even more, to get the ABSOLUTE best performance out of a digital audio setup you should use a master clock device such as the Apogee Big Ben:

http://www.apogeedigital.com/products/bigben.php

Yep, all that $1500 device does is generate ultra-accurate clock signals. Not many consumer DAC's offer word clock sync, perhaps because it's easy to reclock a single source more accurately than to synchronize multiple bidirectional audio streams that one might see in the studio. That's part of the home audio design I've never seen.

Henryhk, if you think about how quickly audio standards and software updates are happening, would you really want to be locked in to one manufacturer's way of doing things? The Linn and McIntosh units are definitely for people with massive disposable incomes that aren't familiar with computers. If that's you, then go for it and let us know. There's a lot more power and flexibility in going with a more open system, though.