Manny:

Thanks for the kind words.

At this point, all the receivers that we carry have built-in DACs. The important thing to remember, though, is that unless you bypass your iPod's DAC, the signal coming into your receiver will be analog, and the receiver's DAC won't touch it.

The Wadia 170iTransport does bypass the iPod's DAC, and send a digital signal to your receiver, which will feed it straight to its own DAC for processing.

Wilson:

Always happy to clarify. Yes, if you want your receiver's DAC (or an outboard DAC) to decode your iPod's digital output, you need to use the coaxial digital cable. The analog outputs let the iPod's DAC do the heavy lifting (should that be what your setup needs).

The analog and the digital audio outputs don't run simultaneously -- and naturally the default's set for digital output. You'd have to select the analog outs each time you dock your player.

Matt:

I'm afraid it's either/or, with the default setting being the digital output. The Wadia dock will output either digital or analog audio, but not both at the same time.

If you want to output analog, you'll have to select that once you've docked your iPod. And you'll have to make that selection every time you dock your player.

Since the Wadia is designed primarily to bypass the iPod's DAC and deliver an unprocessed digital signal to your receiver's DAC, that preference is set as the default. Every time you dock your iPod, the Wadia will assume you want digital output.

Perhaps the solution is to have the feeds for those amps come from the receiver? That output should be analog.

Marshall:

There are some variables involved with your question, but it's all good.

First, by upgrading your sound files from 128 kbps to256 kbps you should have noticed improved audio quality regardless of how you were playing them back. As I was converting my library, I could hear a real difference -- my higher bit rate songs seemed to pop out of the mix.

Even if you hadn't upgraded your library, you should still hear an improvement by using the Wadia dock to bypass the iPod's DAC.

When the folks from Wadia came to visit, they invited us to bring our own iPods to the demo to try out. A few of us deliberately loaded the most highly compressed beat-up sound files we could find. And the Wadia dock made even those test songs sound better by bring out more detail from those 128 kbps and even 64 kbps files. They still weren't great sounding, mind you, but definitely better.

Using higher bit rate files and processing them  through the Integra's Burr Brown 192kHz/24-bit DACs should be a win-win for audio quality.

Matt:

Not sure what's going on with your Onkyo HT-R550 -- there might be one or more things that are causing the problem.

But not to worry. Since you purchased your receiver from Crutchfield, you're entitled to our free Tech support. Just call 1-800-955-9091 and they should be able to help you sort it out pretty quickly.

Dan:

Is using the analog outputs on the back of the Wadia sound just as good as using the digital output? Probably not, because the Wadia 170iTransport doesn’t have a DAC.

It simply bypasses the iPod’s DAC and sends out a digital signal to be decoded by a DAC further down the line – either in a receiver or an outboard DAC. If you use the RCA outs, then the signal is converted to analog by the iPod’s DAC.

If you only have analog inputs into your preamp, a better option would be to go with a different dock that only does analog audio output, such as the Onkyo DS-A2x.

www.crutchfield.com/.../Onkyo-DS-A2x.html

Your other option would be to purchase an outboard DAC for the Wadia to feed into, and connect that component to your preamp.

By the way, another way to improve  the overall sound quality of your iPod's output is to use the highest resolution possible for your digital music files (especially if you're ripping CDs to your computer).

WAV or AIFF are ideal, but Apple Lossless can sound pretty good, too. Even AAC and MP3 files ripped at 256 kilobytes per second (kbps) can sound dramatically better than the same CD tracks transferred at the default 128 kbps.

Nick, you're right. Technically, there should be no difference between Apple Lossless and an uncompressed WAV file in terms of audio quality. (I use Apple Lossless for my own library, BTW).

But some of my audiophile friends swear they can hear a difference, and in various online forums I've found plenty of folks who claim that Apple Lossless files are missing something from the original uncompressed versions.

Since higher level audio is more subjective than objective, I chose to offer a qualified "sound pretty good, too" rather than state categorically that they're sonically identical. If someone's done some controlled testing and side-by-side comparison of waveforms to either prove or disprove this assertion, I'd love to know about it!

Great questions all. I hope I can help. First off, the DACs in most receivers are better than those in MP3 players primarily because they can be larger. Like many kinds of circuitry, performance compromises have to be made as the DAC gets smaller. But don’t let cost be your sole guide. Remember that the cost of an item is a function of many things, including materials, labor, quantities manufactured, etc. The DAC chips found in low-end receivers are made in such large quantities that their cost adds very little to the actual cost of the product. Higher end DACs use more materials, and are made in smaller quantities – both of which drive up the price.

Can you use a receiver DAC instead of an outboard DAC to feed to your NAD integrated amp? Possibly, but it’s going to be messy. You’ll need a receiver that has coaxial digital input for the Wadia, and analog stereo output to bypass the receiver’s amp. While the stereo line-level output bypasses the new receiver’s amp, the signal will still go through the receiver’s preamp. And when it reaches your NAD integrated amp, it will be run through the NAD’s preamp as well. On top of all that, you’re still paying at least $200 or more for all those receiver “guts” that you don’t need.

But as long as you’re having to spend around  $200 or $300, there’s a better solution.

Musical Fidelity’s V-DAC is an outboard DAC that sells for about $299. Crutchfield doesn’t  carry Musical Fidelity products, but they’re readily available elsewhere online. This would give you a high-performance component specifically designed for the function you want, instead of a kluged-together system that makes some bad compromises.

www.musicalfidelity.com/.../vdac.html

Hope this helps!

Dave:

Glad I could help. That's one of the things I like about the comment section. Sometimes during the back-and-forth conversations we help more than just the folks who ask the questions (that's the goal, anyway).

Pierre: Your questions may be basic, but there's a lot of folks that are glad you asked them!

1) How does the 170iTransport get a digital signal out of the iPod when none of the 30 pins in the connector have that function?

Wadia worked with Apple, who had designed a way to get a digital signal out through one or more of the pins (even though that's not their regular function). The dock interfaces with the iPod authentication chip, which then allows the signal to bypass the player's DAC and go straight through said pin(s) to the dock.

2) If it's so easy to capture the digital signal from the iPod, why does Wadia require a box to do it?. Couldn't you run a dock connector directly to a coax or Toslink digital connector?

The 170iTransport's box houses some pretty sophisticated electronics. As outlined above, when you connect your iPod to the dock, the Transport has the necessary circuitry to interface with the iPod's authentication chip and bypass the internal DAC.

And it sometimes does some processing. According to a SoundStage! Review (www.soundstage.com/.../200902.html), when the 170iTransport detects a compressed file, it discards the iPod's clock signal and inserts its own. This can reduce jitter, which makes the music sound smoother, and less harsh.

You can also remotely control your player through the Wadia, which requires some electronics.

Could it all be fit into a smaller case? Perhaps. But remember that Wadia also wanted to provide a stable platform for your iPod. I think that dictated (at least in part)  the size of dock's footprint.

Pierre:

Glad to help.

One thing I wasn't very clear about. Wadia is the first company to have a dock that bypasses the iPod dock for home audio systems. Several manufacturers, such as Alpine, JVC, and Kenwood offer car receivers that do so as well.

Jim R. lists some of them in his blogpost "Car stereos that bypass your iPod's built-in digital-to-analog converter"

http://bit.ly/4xY3sV