If you have a "kick booty" DAC, does the transport

really matter as it is just a "reader" correct. Am I over simplifying it. When you plug your player into an outboard DAC don't it bypass the internal dac and stuff and shoot it to the outboard? Isn't the laser just reading the 1010101 on the disc and shooting the data to the DAC? If this is true can't a Joe just get a whatever player with coax/i.r./esbu out and just invest in a high horsepower DAC?
Like anything else here it will boil down to do you feel it WILL help, you may not hear a diffrence and it certainly wont be night and day....but maybe you will hear a better sound, or atleast think you do. I know guys that use Sony DVD players as transports and they sound awesome into a DAC.
Theoretically, that should be the case. However, practical experience tells us otherwise. I'll leave it to the "digit-heads" to try and explain a reason. All I can say is that I've tried multiple different transports using the same DAC and they do sound different.

Several times I've tried to consolidate my system by using a quality DVD player as the transport for video and to feed an outboard DAC for 2-channel. I never could get it to match the performance of any of my other CD only transports.

I'm sure there are some good inexpensive transports out there, I just haven't heard one yet. There was a <$100 Aiwa changer a few years ago that got great press. Also, there was a <$20 used NEC multispin CD-rom drive was said to be very good.


I've always been of the opinion that if a transport really does make a huge difference, then we need to move rapidly to a different read/transport mechanism than the traditional transport. Reading from digital media and delivering to a high quality DAC should be a straight-forward, extremely reliable process.

I've always been very satisfied with Sony DVD players as transports, but drive most of my music from a music server with a digital output now. Once ripped from the CD to the HD, getting the information off the disc and out the digital output should be error free. If you use a USB DAC, then the USB interface introduces synchronized clocking and two-way communication which, again, should allow for error free transfer. If it didn't work reliably, then you wouldn't be successful using USB ports to transfer data to an external HD, or camera, or whatever.

I will admit to never spending much time experimenting with different transports or digital cables - the bit of experimenting I did do didn't yield many differences of any magnitude, and it was clear to me that digital source would gravitate to HD-based systems, at least for me. Maybe transports and/or cables make a difference - I still wouldn't spend any extra money on a dedicated transport at this point.
Does the transport really matter? In my experience, yes, at least as much as the DAC itself. Even with a jitter-reduction box in between, and a balanced connection, and extensive power conditioning all around. And my admittedly limited experience has been that the mere fact of taking the data off a hard drive, rather than disk, is no panacea or guarantee of superior results either. Every change to the digital front end I've tried was clearly heard at my ears, including digital interconnects, power cords, and transports/players. But my Theta DAC was a hot ticket 10 years ago, and while my tests during interim have comforted me that it's not obsolete by my own standards, take my observations for what they're worth in light of your definition of "kick-booty". Still, if transports didn't matter today, then why would the world's latest and greatest disk-playing gear continue to place a premium on their functional integrity?
Yes it matters very much.
It all starts at the Extractment of the Data.
A DAC's limiting factor, is the quality of the data its fed.

My experience:
Had a separate DAC and transport. The DAC was an Adcom 700 and the transport a rotel stand-alone transport.
Then I bought a Sony SC777ES.
The Sony as transport via the same Adcom DAC totally blew away the Rotel transport in all areas.
I sold the Rotel and felt guilty asking money for it!!! The Sony as transport was that much better.
So, IMO yeah, the transport IS very, very important.
My DAC is pretty old, (Counterpoint DA-10a)....still, I could clearly hear the difference between the three players and one dedicated transport I have tried with it.

There would be cases I'd think where you may hear little or no difference for other reasons, ie...your system, or...the two transports are very equal in build...just guessing here?

To be honest, I was surprised myself. The player I had intended to use as a transport is a fairly heavy and well built Technics DVD A-10 that I had no other use for...a cheap little Pioneer wiped the floor with the Technics?

I'm now using an old Kinergetics dedicated transport...it added some meat to the bones that I thought was the Pioneers biggest weakness...kick drums, ect. now have the proper heft.

in theory, a hard drive is just a high capacity disk fixed permanently in a transport, aside from differences in the data retrieval mechanism (laser) and buffer. almost all attributes of a state of the art transport should apply to a state of the art hard drive. imagine using an Esoteric/TEAC chasis and spinning mechanism plus the JVC/XRCD24 data transport process to create a hard drive...that would be one awesome sounding source!
I'm not sure all the attributes are the same - reading a HD reliably is basically a sure thing, while reading a CD in a transport in real-time apparently isn't a sure thing, or even close to it. What is the same, in a standard setup, is the transport from the reading device to the DAC, which is likely to be SPDIF in both cases, which creates an opportunity for error that should be equivalent in each approach. Still, the HD should be somewhere between somewhat and vastly more accurate than the CD / transport combo.

We need ethernet-enabled audio preamps and processors. Any error introduced by SPDIF would be eliminated, and we'd have the same technology from digital source to analog output as is used in bazillions of other applications where perfect transfer of data is considered a given.
i am not so sure that data retrieval from a hard drive is any more reliable than a cd transport when the quality of the disc, laser pickup, and spinning mechanism is the same. according to my very limited knowledge of electronics and computers, read and write errors occur often when spinning a hard drive, although we may not notice the effect of some (software hiccups, delays, crashes...). i believe there is no device that guarantees perfect data transfer available for consumers as of yet.

elements that i think are crucial for data retrieval are:
1. disc quality and condition
2. reading mechanism (laser)
3. speed and stability of spinning mechanism
4. power management
5. vibration control

please correct me if i am wrong.
Keep in mind that the actual electrical signal carrying the data from the transport to the DAC is an analog signal that is sampled at intervals by the DAC. Any corruption of this analog waveform will alter what the DAC "sees" on the link, especially the signal timing, the width of the pulses and the voltage during the sampling windows. Any variations in these can produce jitter (timing variations) in the recovered signal. This amounts to a transformation of amplitude variations in the analog signal to frequency changes in the digital signal. A lot of work has gone into minimizing these effects, but we're still not all the way there yet. For instance, the quality of the transport's power supply will have an effect on the accuracy of that analog signal carrying the encoded bitstream. Think of the output stage of the transport as the output stage of an ultra-high frequency preamp, and you'll start to get the picture. There's a lot more involved than the 1's and 0's.

I use a kick-ass DAC by anybody's measure, an Audio Note 4.1x Balanced Signature worth over $20K, and it makes the sonic defferences between transports and digital interconnects all the more more obvious. I recently upgraded my transport and interconnect from a a $5K combo to a $10K combo, and the improvement was striking.
I could not of said it better!

Gliderguider, doesn't the DAC convert the "1" and "0" into analog signal. Afterall DAC is digital-to-analog converter. I must be missing your point about the already analog signal from the transport to the DAC.

It's actually pretty complicated. At every stage in both the transport and the DAC, digital information (conceptually consisting of 1's and 0's) is superimposed (or "rides") on a modulated analog carrier signal. There is no such thing as a "pure" digital signal in electronics - a digital signal is really just an information-processing abstraction.

The process of digital to analog conversion you describe is better thought of as taking a very high frequency modulated analog signal coming in from the transport, extracting the digital information from the analog carrier, processing this information through the necessary filters and producing a reconstruction of the original sound pressure waves (the "analog").

The point is, at every stage in the process, from the pits on the CD throught the transport, the cabling, and all the circuitry out to the output jacks on the DAC, the signals are analog. The digital information rides along on these analog signals as a passenger. Anything that can corrupt an analog signal can affect the digital information it carries.

The idea that there are somehow 0's and 1's flowing around inside a "digital" component is unfortunately a massive oversimplification, one that leads to notions like "bits are bits" and "the quality of the transport doesn't matter because it's not analog".

It's all analog. Everything matters.
The data is digital from the Transport. You can view that data on a Scope and look at it at a analog standpiont.
Is the complexity due to the nature of how Transports, output stages and cabling is currently implemented for the purposes of digital audio? The notion of bits-are-bits comes, for me, from the notion that in any other application of computers, I take for granted the transfer of a set of binary data from one circuit board to another in bit-perfect fashion. All sorts of things I do every day would not work, or not work nearly as well, if this wasn't the case.

So, my point has always been, if the current transport-output stage-cable is so flawed as to introduce such widely audible differences, why wouldn't we first engineer a basic transport to accomplish in audio what we take for granted elsewhere?

I'm not an EE, so I could easily just be not understanding something. But I collect, route and deliver digital information globally as a profession, and it would just seem that audible mishandling of the data in a three-foot digital audio connection should either 1) be able to leverage the technologies so cheap and prevalent in other digital data applications, or 2) I should be spending huge portions of my day dealing with errors in my data transfer applications, which I don't.
After a lot of tests and money thrown away I can tell you..
the most important part of a digital playback is the Transport...the most expensive also.
Yes it seems logical that a computer HD would read better, try it out and try a "real" good dedicated transport in your system, you wont believe the difference!
Forget about DVD payers with cheap plastic transports and switching power supplies...aargh,

Thank you Gliderguider for that nice explanation, that clears up a lot of things...

Much (most?) of the problem is that the SPDIF interface doesn't carry timing information, certainly not bit-level timing info. The time base has to be recovered from the signal, and that is inherently problematic on a high frequency link. This is why digital cable quality is so much more important that you'd think it ought to be. It's also why quasi-proprietary interfaces like IIS were developed, and why there is curently so much interest in USB - they pass explicit timing information as well as the data, and so should minimize this particular problem.

One further note - the reason you don't have this problem in a computer is because of the "system clock". This high frequency clock signal is fed to all parts of the system, and synchronizes all data transfers, even between boards, at the bit level.

In a system like the standard CD transport/DAC, each box has its own clock and the two are not synchronized. This is a theoretical argument in favour of one-box players. Of course it only addresses one issue (timing), and there are plenty of other ways to muck up a high-frequency signal.
A DAC that doesn't separate itself from the player with its own clocking must rely upon a very expensive player and a very expensive digital cable for the timing and delivery of the bits. That is, for the feeding of the bits to the digital converter chip.

Some modern DACs, in different ways--some more successful than others, have overcome this problem by reclocking the data making it possible to use a wide variety of relatively inexpensive players, including those that play SACDs and DVDs as well as CDs. They can do this with no sacrifice of audio quality on that account.

Of course how they handle the analog signal delivered from the converter chip will always have an effect on the sound.
Cable Quality?... SC Pulse transformers, and cat5 cable will blow many highend digitals out the water! USB has issues too.
Mel, true about the reclocking the data thing, but,
Truth is, It is limited to the quality of the data it's fed. It starts from the Extractment of data from the media.


I am persuaded that, aside from the timing (important to audiophiles), a bit is a bit. Why do I think that? Because the CHEAPEST CD ROM drive can provide a PERFECT set of bits to a computer hard drive every time. If that were not true, and it made a mistake with only ONE bit, the computer program copied would crash.

So the bits are there, and a modern reclocking scheme can feed them to the converter chip exactly as intended without reference to the "extracting" unit.

And my ears tell me it works.
I have used an old sony CDP75ES (1991) as a transport via toslink out to an ultrajitterbug which reclocks and converts it to a digital coaxial out to my McCormack dac-1 deluxe. I've also used a modified PS audio lamda 1 transport (lambda 2 specs with new laser and board) to the McCormack dac alone and also through the ultrajitterbug. The sony is very good through the ultrajitterbug (terrible without it) but the lambda is still better used alone or through the ultrajitterbug. It is smoother overall with a more natural treble, and better defined lower midrange and bass. The transport does make a difference especially the clock function (jitter control) and output amp section.
Here is something semi-technical to read:
How would you make the Digital reciever faster?