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Matching Woo Audio 6 with DAC

post #1 of 13
11/9/09 at 12:47am
Thread Starter 
I've had my Woo 6 for a couple months now and I am beginning to get ready to drop for a dedicated DAC. The Woo is fully upped (PDPS, Sophia, premium component upgrade, etc.). Headphones are Senn HD800's. All feeding from a music server to my media comp that uses an ASUS Xonar Essence STX soundcard.

I am looking at the following:
1. Meier Corda Stagedac
2. Channel Islands VDA2 with power supply
3. Red Wine Audio Isabellina DAC

The Isabellina is a bit over double the price of the other two, perhaps not quite that. And it's almost beyond what I am willing to spend, but I might splurge because I'll have whatever I buy for years.

Each of these three DACs is really praised by their owners. There is hardly a bad word said. There are probably a million reasons why any one these is a perfect match for the Woo and the Senns. So I'm looking for votes, and arguments in favor of one of these three (or something else). Again, consider the total system and what would go well with the other components, especially the Woo. $1500 is the limit of what I will pay, give or take a few bucks.

I listen to everything from rock, to classical, to ambient, to drone, to electronic.
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post #2 of 13
11/9/09 at 1:08am
I recently got to hear my Buffalo Sabre32 and HD800’s through Covenants W6SE. We did direct A/B comparisons against his pico DAC. We both concluded that the Sabre32 was a fairly big improvement.
I do prefer the HD800 with my balanced Beta 22, the W6SE seems a little softer edged and does not have the last bit of air in the treble, although the W6SE has better overall tone, it could just be tube vs solid state preference. Both amps are exceedingly good.

I would add the Sabre32 to your list of possible candidates.
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post #3 of 13
11/9/09 at 1:13am
If I were you I would avoid a laid back DAC. I don't know what the characteristics of those DACs are but I think the WA6 pairs better with a slightly forward sounding source. Not bombastic or anything just a bit forward sounding.
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post #4 of 13
11/9/09 at 1:25am
Quote:
Originally Posted by johnwmclean View Post
I recently got to hear my Buffalo Sabre32 and HD800’s through Covenants W6.
WA6SE. Get it right

But anywhos, I concur with John. I haven't heard the DACs you've listed in your opening post, but I have compared the Pico DAC against the Benchmark DAC1 USB and AMB's Y2 DAC, and concluded that:

A) The 6SE is transparent to source changes, the tubes don't "gloss over" the benefits of a better source, and
B) The Sabre32 is head and shoulders above all 3 of the DACs I compared against.
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post #5 of 13
11/9/09 at 1:47am
I've used CI VDA2 for 6 months and since upgraded to Ref1.

Ref1 makes the jitter pretty much non-issue, even though a good transport still helps a bit.,

VDA-2 doesn't do the reclocking. If you have a good transport, then vda-2 is not a bad choice.

If not, I'd go with Ref1 or Buffalo32 which is well regarded. I personally wouldn't mind getting Logitech Transporter though. It's quite a good dac, and I personally can't tell the difference between Transporter and Ref1 when I auditioned in Googlephone's place.
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post #6 of 13
11/9/09 at 5:31am
Quote:
Originally Posted by Covenant View Post
WA6SE. Get it right
Whoops, edited as per your correction.
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post #7 of 13
11/9/09 at 7:25am
If you love the sound of tubes you will love non-oversampling NOS DAC's too with a tube output
Go for a Isabellina DAC or a MHDT Havana with a WE396A
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post #8 of 13
11/10/09 at 6:23pm
I just got a chance to hear my friend's MHDT Havana and imo that would be the perfect DAC for the WA6. My second suggestion would be the Monarchy NM24.
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post #9 of 13
11/11/09 at 1:16am
Thread Starter 
Lot of people seem to love the MHDT Havana.


Dan Lavry comes out hard against non-upsampling/non-filtering dacs which kind of gave me pause.
Quote:
The short of it:
1. The DA anti imaging filter required for elimination of aliased images for say a 44.1KHz CD format is very demanding!
Say you want to achieve only 60dB rejection at 20KHz, and you want to have a 3dB bandwidth at 20KHz (-3dB attenuation at 20KHz). A circuit designer can recognize that you need tons of filter poles, which would lead to about dozens of op amp stages all with precision parts (a lot of 1% caps and resistors and possible hand tweaking ...).

2. Say you have done such a crazy filter (and 60dB is a pretty poor filter to start with), then you have an additional attenuation of about -.7dB due to the sineX/X effect (see my paper at bottom of page 3).

I am not an advocate of huge upsampling ratios, but clearly, some upsampling is in order. As soon as you go X2, much of the filter requirement is gone (roughly 12 times easier job, because the transition range went from about 2KHz to 24KHz). Also, most of the sinX/X problem is gone, or is at least "easily correctable".

Anyone that uses a non over sampling DA, and thinks it sounds good are saying 2 things:

1. They like the upper band to be attenuated significantly, and they like the associated phase shift that comes with it (all the way down to 10KHz...)
2. They can stomach aliasing, especially into the higher frequencies.

I do not intend to argue likes or dislikes. But if the intent od a DA is anywhere near converting digital to analog with minimum of distortions, the upsampling DA is inherently a better way to go. And let us no forget that aliasing distortions are not harmonic, thus very non musical.

My best guess is that one can "stand it" if they filter out the higher band. One can use a very high order EQ (which will also cause undesirable phase non linearity).
and

Quote:
A DA without a filter introduces image energy that is nearly as high as the energy in the audible range. In the case of non up-sampling DA, the audio content is centered at the sample rate, twice the sample rate, 3 times…. And it goes up to very high frequencies. The amplitude decay curve is rather slow…

Assuming that you could not hear above 22KHz, you say that the image energy will not be heard. But in fact, the DA output signal, both the audio and the images at frequencies above audio must go through some electronics before reaching your ears. Such electronics may be a preamp, a power amp, a speaker, a headphone amp and a headphone… or in a music production environment the signal may be sent to an analog mixer…

It is one thing to ask an amp, or a speaker (or whatever gear is there) to “process” a signal with energy content that is limited to 20Hz-20KHz (or say 10Hz-50KHz) accurately. It is another thing to expect accurate results when the signal contains relatively high energy at high frequencies. When you try to do that, you will find out that the image energy interferes with the electronics in many way. It degrades the transfer curve, which causes inter modulation at all frequencies including the audible ones, it can ruins circuit badly.

If you did not understand what I said, here is another view, perhaps more intuitive: The DA output signal BEFORE the filter is typically (depending on the signal) made out of a very fast steps, and for some signals, the step amplitude is high (think of say sampling a 10KHz full scale sine wave). Fast changes are made of high frequencies. The electronics after the DA would have a “difficult time” tracking those “fast steps”. An anti imaging filter will “smooth out” the signal so that the signal will move much slower, and without the sudden “jerky” steps. Such a signal happened to represent the original waveform before it ever hit the first microphone…

Then comes the other point: a DA with no up sampling has very non flat amplitude vs. frequency response. In theory, a DA is perfect, because the samples are “zero width”, each sample with proper amplitude. But in practice, zero width samples, or very narrow pulses, carry very little energy, so the outcome will be very weak. A weak signal calls for a lot of amplification, which raises the noise, and that is undesirable.

So instead of narrow pulses, we go for a “stair case” waveform, where each value is held steady until the next sample. That practice (we call it NRZ for “not return to zero). We do so instead of the theoretical narrow pulses (we call them RZ because with a narrow pulse the signal between samples is zero most of the time).

Now, doing NRZ (stair case) solves the noise problem, but it brings on another problem – it causes some attenuation when you get to higher audio frequencies – nearly a dB at 20KHz if I recall (see my paper on Sampling, Over sampling, Aliasing, imaging). That roll off curve (sinX/X shape) is NOT something you can fix with an analog EQ (poles and zeros). When you up sample, that problem goes away. See the graph in the paper I recommended.

I could say much more, but those reasons are more then enough to explain that non up sampling has problems, and why no filter is bad news.
http://recforums.prosoundweb.com/index.php/t/13252/0/
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post #10 of 13
11/11/09 at 1:46am
u already got a tube in your setup. I'd get a SS dac if i were you.

VDA-2 is very good performer and you can get it around $400 used. Hard to beat that for a price. If I didn't know Ref1, I would have been happy with VDA-2 just as much.
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post #11 of 13
11/12/09 at 12:52pm
Thread Starter 
Hi everyone. Thanks for all the feedback. After a great deal of additional research and inability to make up my mind I have decided to go for the Corda Stagedac. It provides significant options to tweak (see linked manual) while being very well-reviewed. I really like the tweak the options, I can run it as a pre-amp to the WA6, and I am very curious about the improved cross-feed. The fact that it is under $1K is a nice as well.

These helped make up my mind:
http://www.head-fi.org/forums/f7/mei...agedac-426367/
6moons audio reviews: Acoustic System Int. HeartSong Rack

Manual for Stagedac - Very interesting options.
http://www.head-fi.org/forums/6031943-post196.html
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post #12 of 13
11/14/09 at 3:57pm
will be interested in your comments on the stagedac. it is on my shortlist!
i also fancy adding a tube amp next year, the woo is on my shortlist too.


Quote:
Originally Posted by Speederlander View Post
Hi everyone. Thanks for all the feedback. After a great deal of additional research and inability to make up my mind I have decided to go for the Corda Stagedac. It provides significant options to tweak (see linked manual) while being very well-reviewed. I really like the tweak the options, I can run it as a pre-amp to the WA6, and I am very curious about the improved cross-feed. The fact that it is under $1K is a nice as well.

These helped make up my mind:
http://www.head-fi.org/forums/f7/mei...agedac-426367/
6moons audio reviews: Acoustic System Int. HeartSong Rack

Manual for Stagedac - Very interesting options.
http://www.head-fi.org/forums/6031943-post196.html
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post #13 of 13
11/15/09 at 1:56pm

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