Can We Start at the Beginning? iMac, iTunes and wifi

[bobg]

Greetings,

 

I am setting up a new 2 channel system that will be used exclusively to listen to iTunes songs (all lossless ALAC) stored on my 5-6 year old iMac (3.06 ghz dual core, 4 gb RAM) using an Emotiva XDA-2 DAC/pre-amp hard wired to a local amp. I also will be sending the music over wifi (Airport Extreme and Airport Express) to two other sytems in other rooms. The airport Express' will be connected to other pre-amps by RCA, as they do not have optical outs, I don't think.

 

My initial question has to do with the base iMac connection to the DAC. What factors do I consider in deciding which type of cable to use - USB, toslink or coax?

 

What do I do with iTunes as far as its settings for this purpose?

 

Since I do not have any hi-res files and probably will not be getting them, will I benefit from software like Audirvana, etc? Bear in mind I know little about computers and simplicity and reliability is a big factor to me, but so is sound quality. I assume I will need to balance those factors somehow.

 

Your shared thoughts are appreciated. Thanks

[Paul R]

Greetings,

 

I am setting up a new 2 channel system that will be used exclusively to listen to iTunes songs (all lossless ALAC) stored on my 5-6 year old iMac (3.06 ghz dual core, 4 gb RAM) using an Emotiva XDA-2 DAC/pre-amp hard wired to a local amp. I also will be sending the music over wifi (Airport Extreme and Airport Express) to two other sytems in other rooms. The airport Express' will be connected to other pre-amps by RCA, as they do not have optical outs, I don't think.

 

My initial question has to do with the base iMac connection to the DAC. What factors do I consider in deciding which type of cable to use - USB, toslink or coax?

 

What do I do with iTunes as far as its settings for this purpose?

 

Since I do not have any hi-res files and probably will not be getting them, will I benefit from software like Audirvana, etc? Bear in mind I know little about computers and simplicity and reliability is a big factor to me, but so is sound quality. I assume I will need to balance those factors somehow.

 

Your shared thoughts are appreciated. Thanks

 

Here's my opinion- based on your specifications. It is important to note you do not plan to go to high-res music - things change if you do!

 

The "base iMac" connection to the DAC - if you can, definitely try all three connections. It is almost certain that one or the other of those connections will sound better to you. Use the one that sounds the best. A $15 Belkin Gold USB cable is plenty good enough to use for USB, at least to start with. Pretty much any good quality optical and 75ohm coax cable will serve for the other options. I doubt you will have much trouble deciding which one you like the best.

 

In iTunes, you just select the output device for music in the Settings -> Sound -> Output tab under Preferences. That's pretty much it.

 

For the remote Airport Express devices, you can choose between using the little DAC in the airport and bringing the sound out with a stereo mini to RCA cable (Audioquest makes one of these for under $20 I think), or using an optical cable into a DAC or Receiver. The Airport Express devices have optical outputs that are accessed from the same jack as the stereo mini output.

 

Using Audirvana+, Pure Music, Amarra, or bit perfect may improve the sound to your "base iMac and DAC", but they may also screw up sending sound to the remote locations. Honestly? I would avoid them if and until you decide to do some upgrading.

 

Hope that helps a bit. I expect your setup will sound very good, though sooner or later, the upgradeitis bug will bite you.

[mwheelerk]

I don't believe you can make a direct connection from an iMac to a DAC using a 75 ohm digital coax. It would require a USB to Coax conversion. For the optical it will need to be a mini optical to optical or again an adapter from mini to standard optical.

 

I use to use my 2007 iMac and my experience was a preference for the USB connection to DAC but as Paul has said it really best to try the options for yourself and decide on your preference.

[bikemig]

The Apple express really benefits from an external dac.

[dc2bluelight]

The airport Express' will be connected to other pre-amps by RCA, as they do not have optical outs, I don't think.

 

All Airport Expres and Extreme units have optical outputs. It's the same 3.5mm jack as is used for analog audio, you use a mini optical cable.

My initial question has to do with the base iMac connection to the DAC. What factors do I consider in deciding which type of cable to use - USB, toslink or coax?

Coax is not an option, it's optical or USB. Both can work, there are advantages to each. One consideration is that optical breaks a potential ground loop with your other audio gear. It's usually not a problem with Apple products, but just in case you do get odd hums or noises, even with no audio playing, try the optical and see if that gets rid of it.

What do I do with iTunes as far as its settings for this purpose?

Nothing in iTunes itself. With iTunes in OSX, the basic audio output device is selected in the System Preferences (Apple > System Preferences > Sound), but that's good only to select the output and input devices. Actual sound device settings are found by launching the Audio Midi Setup application (Applications/Utilities/Audio Midi Setup), which will let you pick the default sample rate and bit depth for for your audio device of choice. iTunes then uses those choices and settings. Since your files are ALC (when you ripped, you set iTunes for 44.1, right? Hope so!), the native setting would be 44.1/16, though the system can up-sample on the fly to 96/24. Not much to be gained, though. It's "bit-perfect" already at 44.1/16.

 

The Apple express really benefits from an external dac.

 

He means Airport Express, and possibly. The on-board DAC isn't the world's best, but is more than adequate for casual and background listening. And, if you plan to use multiple Airports to feed zones around the house with lesser playback systems, the on-board DAC is just fine. External DACs connected via optical to an Airport may sound a little better, but only if you're listening critically. That also drives the cost per zone way up. Also, lossless streams from iTunes to Airport devices is limited to 44.1/16, regardless of what your system sound settings are. So it's bit-perfect at the optical out of an Airport unless there were higher res files in the library, which will be down-sampled on the fly, on the way to any AirPlay device.

 

But don't obsess for background music, or the usual "whole-house audio" application.

[Paul R]

Of course all the posters are correct with their corrections.

 

To use Coax cable you will need an adapter, with a USB to SPDIF adapter or an Optical to Coax adapter. You did not really specify the DAC you wanted to run on the main system , so I figured you probably would know that bit. Apologies.

 

The default setting for output sample rate and bit depth is 16/44.1, so you should not need to adjust it, but it is always a good idea to check it as well.

 

Yours, Paul

[dc2bluelight]

Of course all the posters are correct with their corrections.

 

To use Coax cable you will need an adapter, with a USB to SPDIF adapter or an Optical to Coax adapter. You did not really specify the DAC you wanted to run on the main system , so I figured you probably would know that bit. Apologies.

But what would be the point?

The default setting for output sample rate and bit depth is 16/44.1, so you should not need to adjust it, but it is always a good idea to check it as well.

Good advice, check it. It's not really a "default" because there are a lot of things that might change it.

[Paul R]

But what would be the point?

 

Some DACs sound very much better when fed from one input or another. A Peachtree DAC*IT original DAC sounds quite significantly better over Coax or Optical than over USB. And Coax sounds just slightly better than Optical.

 

An old AVA Transcendence 8 DAC only has Coax inputs, so one would have to convert USB or Optical to that, but it sounds very good indeed.

 

Good advice, check it. It's not really a "default" because there are a lot of things that might change it.[/Quote]

 

I didn't know that, I though it was always set to default to red-book as long as the DAC can accept it. Learn something new every day - thanks.

 

-Paul

[dc2bluelight]

There's no reason one connection method would sound different from another because of the style of connection, apart from a badly designed interface at the DAC. That's not small, however, people slop up on the details all the time. But some do it right. For example, a Motu 4-Pre uses a data reclocking method to eliminate jitter. It's on both USB and FireWire. And as a result, both sound identical...pretty sweet I might add. Other devices might not reclock one or the other. I see no point in converting USB to Coax if USB is available both ends though, especially if the DAC has asynch. Bit for optical vs usb, it's certainlu device specific, so got to give them both a shot.