How important is the transport when using a DAC?


I've been thinking lately, if my transport is extreme low-end, is having a nice DAC a waste of time? In other words, if I am using a $60 Sony DVD/CD player to deliver the digital signal through a coax cable to my Arcam r-Dac, is that not doing it justice? Do you recommend I upgrade my transport to better meet the quality of the DAC or does it not matter?


I guess that all depends on what and where you want to take your system.

This has been discussed many, many times here, and the answer is always that the transport makes a big difference.

What that means to you, you'll have to decide.

Hi LearyScott

I had a $30 Memorex DVD player as a transport to a Musiland MD-11 DAC and this combo was very un-involving. When listening to music all I could picture in my head was grey cold steel. I later changed the transport to a Cambridge Audio CD player that had a significantly better build quality and the overall sound improved. YMMV.

What transports are you eyeing?
maybe borrow a better transport from a friend and spend a sat. afternoon investigating.
Krell man,
Well...if there ONE thing you can get away with not having to spend loads of money (unless ultimate musical reproduction is a must), inexpensive transport it is...but experiment with few inexpensive dvd players and you might hear a difference too...
I would really welcome someone demonstrate this difference in sound for me. I have yet to hear it.
Many fairly high end CD players used to use 29 dollar computer transports.

Then again, they are selling Cardas Gold CAT5 cable now for music go figure...
not sure how to "demonstrate" it for you Gumby?? (without inviting you over with a cheap transport in hand). i've hooked up several cheap transports/cd players to my PWDmk2 and they all sounded obviously worse...compared to my PWT.

can't/won't make the blanket statement that a better transport will yield better sound but it absolutely did with my PSA gear. true...the PWT is a 3k transport and the question of "how much better" or "is it worth it" can still be debated. but make no mistake *can* make a very noticeable difference.
The answer to your question is yes, you should have a transport that is well matched to your DAC because the system sound will take on the character of the transport. One of the better transports available at a reasonable price is the California Audio Labs Delta transport. I know of one currently for sale. If you check around you will find it.
We are dealing with "systems" and like all systems, they are only as good as the weakest component. The answer to your question is going to require listening and comparing different components in your system. The effort should give you what you are looking for.
If you are going to use a dac then a good transport is always going to make a big difference. I've experimented with the concept over twenty years and you need a good transport to hear what your dac and system is truly capable of.
Very much a function of the overall architecture. With reclocking and asynchronous DACs, the difference are definitely a lot smaller then with a traditional synchronous architecture. It is still a bit of a mystery to me why a transport would make any difference if the bits are fed into a buffer and then completely reclocked, but I guess they still do.
Newbie chip in here: normally when using standalone DAC, I would think people have a pure digital system, with some sort of transport like a computer or squeezebox to feed into the DAC to play the ripped lossless files. Alternative path would be a decent CD player with DAC built in. What the advantage of having a standalone DAC but still use CD player instead of lossless files ?
02-14-13: Edorr
Very much a function of the overall architecture. With reclocking and asynchronous DACs, the difference are definitely a lot smaller then with a traditional synchronous architecture. It is still a bit of a mystery to me why a transport would make any difference if the bits are fed into a buffer and then completely reclocked, but I guess they still do.
Good comment; good question. I suspect that one reason a transport can still make a difference if the data is completely reclocked is that digital noise associated with the low-to-high and high-to-low transitions (i.e., the risetimes and falltimes) of the signal that is received from the transport can to some degree couple past the buffer circuitry and contribute to jitter at the point where D/A conversion is performed. The coupling occurring via grounds, stray capacitances, and other possible paths through the circuitry.

The magnitude and character of that kind of effect figures to be dependent on unspecified and/or unspecifiable design characteristics of both components, and also the interconnect cable, and to not have a great deal of predictability.

-- Al
Almarg is correct. What he is referring to is sometimes called a glitch. it can create noise modulation and time smearing that is not corrected for by resampling. Also since the signal from transport to dac is an analog signal (not digital as most people think) the cable can introduce noise that is not totally removed by reclocking
Alan, thank you for seconding my comment. But I would question the reference to the transport's output signal as being analog. Both S/PDIF and AES/EBU signals combine clock, data, and other information into a biphase mark encoded signal. The data that is embedded in that signal corresponds to the 1's and 0's which digitally represent the original analog waveform.

See, for example, page 2 of this paper, starting at the middle of the page.

-- Al
Is anyone familiar with the Arcam rdac? It looks pretty basic with coax, toslink and usb inputs. Outputs are by way of a single pair of RCAs. It is advertised by Crutchfield as being an improvement over your sound card and it sells for $479 delivered. The Sony DVD player currently being used as a transport is murky sounding at best. Unfortunately Arcam does not make a transport. They decided to make ipod docks instead. It is interesting reading all of the technical information, but does anybody have a recommendation for a transport to be used with the Arcam rdac?
Not important at all for me. But hey, I'm way biased since I ripped my CDs using a Samsung Blu-Ray Disc reader > Mac Mini/Pure Music > Meicord ethernet cable > Apple Time Machine > Squeezebox Touch SP/DIF > Metrum Acoustics DAC >.

Even though my priority media is vinyl I'm finally enjoying a much more relaxed digital presentation by not using my ModWright Truth modded Denon 5900. I tried the DAC after the Player but streaming is clearly better. So in my opinion, you may not doing your DAC justice.

If I were digital only I'd sell all my front end gear and go with the stunning Empirical Audio Overdrive and be done with it.
First, all of you need to understand that there is no perfect "reclocking" system in any DAC. They all have drawbacks and imperfections that make the majority of them still sensitive to jitter. Maybe not as much as a DAC from 15 years ago, but still sensitive.

IMO, a lower jitter transport or reclocker after a transport is ALWAYS a good idea. If you read the reviews enough you will find that the reviewer with the low jitter source concludes that most DACs sound virtually identical when driven from this source, even $1K and $8K DACs. The conclusion is that the jitter of the digital source is actually more important than the DAC. It has actually always been the case.

Steve N.
Empirical Audio
In my opinion the analogue stage is more important. I owned two Tandberg CD players. These were top of the line CD players selling in the neighborhood of $2,000 in the late 1980s. These CD players were identical in every way except one player was 14 bit and the other player was 16 bit. I compared these two CD players over and over again. However, I was unable to distinguish a difference between the two CD players.
I've found the transport to be as important as the DAC.
Rrgog - Maybe there was no difference in jitter between the two CD players. There were both probably high in jitter. Also, you were likely using an inexpensive active preamp. This will easily mask any differences there. By inexpensive, I mean less than $15K. The best active preamps are tube.

One thing that you all can do to improve the resolution of your systems is to sell the active preamp and reaplce it with a transformer passive linestage (TVC). These beat 99% of active preamps.

Steve N.
Empirical Audio
These days, its the least important that it has ever been. Cd transports are pretty much commodity items these days.
Audioengr, In 1990 there was no such thing as a 15K preamp. For what it's worth, the same chip set used in that Tandberg CD player back then is highly desirable today for it's musicality. I think Philips was on to something when they were developing the CD. After all, in the mid 1980s, when CDs were being introduced, they had to compete with Vinyl and Reel to Reel tapes. Since those early days the sound of CD players have changed and not necessarily for the better, only different. Also, Your comment regarding any preamp costing less than 15K is considered inexpensive is ludicrous and I am totally against commercial users pushing their products on these threads.
I'm surprised no one has mentioned slaving, yet.
The new DACs, using the latest digital input receivers, are far less sensitive than the DASs designed a few years back.

If only your player has a bit perfect output, I think you will get a bigger improvement by adding a quality linear power supply to your rDAC. The Teddy Pardo one, which is based on a super regulator solution, takes this DAC to entirely different level. Having had a lot of experience with this DAC, I cannot recommend this solution highly enough.

I also highly recommend using the rDAC via the USB in as it sounds best This way.
Thanks for the responses guys, this has been a very interesting discussion to read through. There's a bunch of terminology that I am completely ignorant of that I have to investigate. But I think I may have answered my own question. I made a subtle upgrade to the transport and the connection and I am hearing a world of difference! I replaced the $60 dvd/cd player with a Playstation 2. I know this is splitting hairs, but I'm hoping theres a build quality difference considering theirs a several hundred dollar price difference. Also, I switched from using a coax cable with the cheapo dvd/cd player to a toslink cable with the PS2. This is my first time using toslink with my r-DAC. I think the overall presentation is softer and less ear-fatiguing. Very pleased with the outcome. Next up just gotta upgrade this vintage Pioneer SX-750....Cue the audiophile eye rolling!

Rrog -I dont manufacture or sell preamps.

Steve N.
Empirical Audio
Slaving is only possible with a tiny set of sources and a tiny set of DACs that output master or word clocks. Thats why. Its also no guarantee of greatness. You are at the mercy of the DAC designer and the clock and clock circuit that he designed.

Steve N.
Empirical Audio
Scott - I hope it is a good 1.5m glass cable, not a short plastic one.

Steve N.
Empirical Audio
Audioengr, What is an Empirical Audio DAC/Pre?
I recently went from a Marantz SA11S2 to an Ayre C5mp , being used as a transport only ( except for SACD's ) and found the improvement striking to say the least . There was such a big improvement in all aspects of the sound that I had to re-evaluate my long term preconceived ideals .
Rrog - see


Steve N.
Empirical Audio
Elberoth - I recentky had the opportunity to do a shootout of several liner and switching supplies powering digital, USB converter, reclocker and DAC. In all cases, the switching supply followed by a fast regulator beat out the linear. I feel now that liners are just too slow to respond to be interesting for digital.

I have also had customers try various linear supplies for the Synchro-Mesh reclocker, all with dissappointing results.

Steve N.
I don't believe for a minute that linear power supplies are too slow for digital.The lastest ModWright 105 OPPO and the Yamamoto YDA-1 DAC (two fine examples) use well built and implemented linear power supplies. If the criteria and goal is pure natural music reproduction and involving musically and realism, I'd put these two excellent digital components up against any alternative with switching PS in terms of actual sound quality. What are some examples of these newer and better switching PS digital components? I'd like to hear them and compare.
The linear powersupply in the Oppo 105 is only used for the analog section. However, some manufacturers (Ayre DX-5 - Theta Compli 3D) have put linear PSs in Oppo based players for the digital section, apparently with good results.
That's debatable. Compared to what?
Charles - there is a big difference between a switcher and a good quality switcher followed by a fast discrete linear regulator.

Steve N.
Empirical Audio
The ($4000) Theta Compli 3D is basically an Oppo 93 with a Theta faceplate and a linear powersupply and all the analog circuits ripped out. According to its owners it sounds quite a bit better than the Oppo 93.

I personally also have a linear powersupply in my Oppo 93, but never did an A/B comparison with the old powersupply.
MSB is another example I've heard several times recently that utilizes a quality linear PS and provides that natural realistic sound with exceptional tonality. I like to know what digital sources have this desirable presentation with a nonlinear PS.
One thing I learned to avoid (and dismiss if others make them) in audio is making categorical statements about the inherent superiority of one technology over another.

It is probably possible to build a fine sounding DAC using both a linear and a switching powersupply.
Ed - Ive tried several linears and none of them work well for digital. Analog maybe. Even LI batteries with ultracaps in parallel are not as good.

Until you have heard a good switcher/series regulator, you cant possibly understand. Believe me, the difference is incredible. There are none like this available on the market yet BTW.

Steve N.
Empirical Audio
Steve, the best digital I have heard (by a mile) is the MSB series IV. A lot of people that have listened to every 5 figure DAC under the sun concurr. It uses a linear powersupply.

May be a better mousetrap using your switcher/series regulators is just around the corner. Who knows. Technology moves on.

For now, all I can say that if the best sounding DAC money can buy uses a linear powersupply, it is premature to write it off as technology unsuiteable for digital applications.
Did I just read (again) that a power supply is better than a chemical battery to provide DC to a component?

This sounds like the Naim dealer who insisted two car batteries would not run a preamp. The 24 volts would not be "clean enough" and the performance would suffer.

Sorry to sound sarcastic...and I am not claiming to be the end all guru here, but a battery is perfect DC, is it not?
Especially for a preamp or DAC/CD player application which is essentially a stable load.
Yup, I agree the best is MSB and it is linear go figure.
Gummy - this is about di/dt. Batteries have non-zero internal impedance and even with ultracaps they cannot compete with fast low-impedance regulators. The issue is having the same impedance at all frequencies of current.

I have designed and sold both SLA and LI/ultracap supplies in the past.

Steve N.
Emnpirical Audio
But isn't the variance caused by the dynamic nature of the power demand?

I get the transients and "current derivative" or what some in slang call "load backlash," but this is microscopic, no? ...and from what I know, the down-line component would almost have to be "designed" to place the onus on the supply, would it not?

This is the hairy edge of my knowledge and I intend to learn more about it. Answers to the above will help if you have the time.

Coming from a "battery is purity" background...this will be a learning experience.
Gumby - yes, di/dt is the change in current over time. It is the dynamics changing load and resultant current. If the load changes and the regulator cannot respond quickly enough, you get distortion, lack of focus.

This is by no means microscopic. It is a function of the power supply AND the power decoupling at the load and all of the wires and traces bewteen the two.

LI batteries, particularly combined with ultracaps can outperform most regulator designs except the very best.

Its the very best discrete regulator designs that I use. They are faster than the best LI battery supply and very low noise. Critically damped, so no overshoot when responding to transient load changes. These are designs by Paul Hynes that have been optimized by me for digital.

Steve N.
Empirical Audio
OK, this is late in the game for this thread and slightly off topic, but the insights provided here may be helpful to me. I have an Arcam AVR400 receiver and have been trying to set up a modest music and HT system around it and Monitor Audio Apex A40 fronts and Apex A10 rear speakers and B&W PV1D sub. I currently have and old Yamaha CD player but was hoping to be able to use my Blu-Ray player as a transport with the Arcam internal DACs at first and eventually upgrading to an external DAC for two channel.

Multichannel DTS and Dolby Blu-Rays on a Panasonic BDP and CDs played on the Yamaha sounded great through the Arcam, but the Panasonic as a transport for Redbook two channel using either HDMI or Toslink optical cables was not good. Clear but lifeless sound, no swing whatsoever. USB Redbook FLAC files on flash drive plugged directly into the Arcam sounded similarly sterile. I was thinking that the problem was with the Arcam DACs for two channel.

Then my Panasonic BDP quit working reliably, so I replaced it with a new Samsung BD-H6500 which was really well reviewed in Sound and Vision. Using the Samsung as a transport for CDs the sound is completely different, much better, and closer to the Arcam fed by my vinyl analog set up. Good pace and timing, tone, spatial resolution, etc. The Samsung has the ability to feed the Arcam AVR raw bit stream data, and this setting makes a big difference using the Toslink optical cable.


Thanks in advance for any insights.

One thought occurred to me. For the difference between the CD sound and the flash drive, am I just hearing the difference between ripped FLAC files and the digital files on the original CD?
There a lot of variables here. The most obvious is that the jitter when playing 44.1 may be higher. Another is the digital filtering in the DAC, which usually sounds worse at 44.1. Another is the playback software, which has a large influence on the sound of playback of digital files. Another is the ripping software you used for the CD rips to hard disk.

FLAC files do sound a bit worse than native .wav, but you must really have a resolving system to hear this. Its not that obvious. I doubt if this is the problem.

I would recommend to first do the easy stuff, namely the player and ripper. See this for recommendations:

Steve N.
Empirical Audio