[amitm]

Hi all:

I hope this is the correct forum to discuss this, so here goes. I am putting down MY thoughts on what I think is the way to go with DACs and I am then looking for some advice on a recommended component:

In my view, oversampling is necessary for non-hirez files, and I think that it is best done in software on the PC since one can maintain maximum precision there. This is even easier now since there is software such as JRiver available for such purposes, and the recent vintage of desktop/laptop processors are extremely powerful. This eliminates the need for oversampling on hardware, and the focus then becomes parts that are hardware specific: namely, interfacing with the transport and D/A conversion. With appropriate oversampling rates, the analog filter on the D/A need not be very sharp either.

As I understand it, there are two overriding considerations in D/A part once the DAC chip is chosen: Accurate clocking circuitry and a output driver circuit. Of course, a corollary is that the power supply should be good.

On the transport side, I believe that input buffering is the best strategy to minimize jitter. For example, with USB, asynchronous USB forces buffering; however, there is no reason why synchronous USB with buffering cannot be just as good (CEntrance is a good example).

I am sure I am missing some details, but the above is what comes to the top of my mind. Please feel free to add more to it as necessary.

Having said all this, here is where i need advise:
In view of the above, I am planning on going to a PC/laptop based solution for all my digital audio.

Which DAC would you recommend where I can feed 192/176.4 KHz signals, and which has a reasonably good analog circuitry/PS? I do need a USB input at 192/176.4 KHz rates as well.

I am looking at a budget limit of $1500, but can extend it to $2K if necessary.

Thanks.

--amit

[wilsynet]

A few days ago there was a used Ayre QB-9 with 192/32 option for a little over your maximum price on Audiogon. It may still be there.  I'm also keeping an eye on what develops with the Tranquility 192/32 offering which should be coming out in the next month or two.

Otherwise, an Empirical Audio Off Ramp 4 paired with the Eastern Electric DAC Plus, run with tube removed and opamps rolled seems very intriguing.  Although perhaps the Off Ramp isn't strictly required.

Every few months there's a new DAC offering of note.  Modwright's DAC is also long rumored and due any time now.

If I were buying something right this moment, it would likely be either the Eastern Electric or something from JKENY.  The EE Seems to have quite a following, is high value for dollar, and a few tweaks later ostensibly makes it a giant killer.  As for JKENY, I'm a big fan of what he's been doing.

[saisunil]

Hi Amit,

Do look into Zodiac offerings ...
You may want to get a separate DAC and a separate USB Converter but your budget may constrain you ...

I think, USB conversion may change / advance faster than D to A ...

wilsynet has made some good suggestions as well

With computer as source - apparently transport plays a huge role and for that matter mac mini with SSD drive etc. is the one to beat - no laptop Mac or PC has come close ... perhaps a lot to do with the fact that it is headless and minimalist design ...

If you can wait - CES 2012 is around the corner - it is likely to bring new digital products and may be worth the wait ...

Good luck

[eclein]

+1 on the Zodiac stuff, I have not heard but close friends have them and love them, in fact they are pushing me to get one but my budget just doesn't go there.
 You have an excellent budget range though and should find a lot of bang for your buck.

[amitm]

Thanks for all the replies! I will definitely look at the suggestions. Among them, Ayre QB-9 was already on my radar.

You know, Sunil, the only thing is that I am not convinced about is the importance of transport -- the reason being buffering on the DAC makes transport influence moot in my opinion. There is some evidence based on some measurements from Stereophile that transport jitter can influence jitter on the DAC in spite of buffering. I will try to dig up the link. But that is a DAC implementation issue in my view.

--amit

[NIGHTFALL1970]

Amitm,
Check out Frank Van Alstine's Vision Hybrid DAC.  Also, check the "used Equipment" section.  He has a used Ultra hybrid Dac that can be upgraded to an ultra II.  I have one that made a huge improvement to my CDs.

[coke]

I really wanted an AVA DAC but it was above my budget when I was looking. I ended up with an eastern electric and i've been very happy with it.  I also found a used one for sale locally and my dad purchased it for his system.  Both sound great, even with the stock tubes.

[Vincent Kars]

You know, Sunil, the only thing is that I am not convinced about is the importance of transport -- the reason being buffering on the DAC makes transport influence moot in my opinion.

If you have a buffer there is a very hypothetical case that the clock of both sender and receiver are exactly in sync. In practice they differ.
In case of USB there is always a buffer but the method to manage the buffer differs.
In case of adaptive synchronization, the DAC varies the speed of the clock driving the DA to avoid over/under run.
In case of asynchronous synchronization, the DAC runs at a fixed speed and regulates the amount of data send by the PC. This implementation is low on input jitter.
Given your budget, I should look for a async USB implementation.
Obvious a DAC is more than a USB protocol.

[amitm]

If you have a buffer there is a very hypothetical case that the clock of both sender and receiver are exactly in sync. In practice they differ.
In case of USB there is always a buffer but the method to manage the buffer differs.
In case of adaptive synchronization, the DAC varies the speed of the clock driving the DA to avoid over/under run.
In case of asynchronous synchronization, the DAC runs at a fixed speed and regulates the amount of data send by the PC. This implementation is low on input jitter.
Given your budget, I should look for a async USB implementation.
Obvious a DAC is more than a USB protocol.

Thanks for replying to that part of my comments!

Obviously,  the buffer in both cases is effectively a "jitter buffer" (although jitter has a different meaning in this context) -- and  its size is determined by the implementation and/or by the budget (?).

However, there are synchronous DACs even below my price range that have a very small jitter, e.g., see CEntrance DAC measurements in Stereophile. So it can be done well on a "small" budget. I wonder why their kind of methodology is not adopted more because it avoids the implementation of asynchronous USB protocol on the DAC. This presumes, of course, that the computer feeding the DAC is up to the task.

--amit

[Vincent Kars]

As usual, the implementation is more important than the principle.
But one has to write code for a USB receiver anyway.
I do think when done right, async is a better implementation than adaptive.
In principle one don’t want to have the performance of a DAC dependent on the quality of the source.
Isolating the DAC by using a async protocol and galvanic isolation is probably the way to go.
Maybe this link is of use: http://www.audiomisc.co.uk/Linux/Sound3/TimeForChange.html
It is one of the few direct comparisons I know between adaptive and asynchronous synchronization.