Originally Posted by EphemeralHope

but what I really don't get is - how does a DAC make music better if it's just converting? is a DAC ESSENTIALLY an external sound card? I'm really confused at all this still - do I need both or one? Does the DAC rely on the soundcard quality to work with(so if soundcard sucks there's only so much a DAC can do) or is DAC already stand alone ... just confused

Originally Posted by Shahrose

All sound cards have a DAC as well, that's what processes the digital signal from the computer into an analog signal that can be amplified. There is also an integrated mini amplifier on sound cards that accomplishes the latter task.

When people say "DAC" they're referring to an external box that's specialized only for the purpose of converting a digital signal to an analog one. You probably already know that a device specialized for one task will be better at it than a device that does multiple tasks such as a soundcard.

If you're using a computer and want to use an external DAC, you still need some way to transport the digital signal to the DAC for it to work. This is accomplished by a soundcard's digital output (many integrated motherboard soundcards have these as well, albeit of lower quality). In this case, the soundcard is acting as a transport and relegating all the D/A conversion to the external DAC by providing it the digital signal. This means, pretty much any decent quality soundcard will provide the same SQ as it's not doing anything but transporting the signal to the DAC.

Some external DACs also run off USB, which eliminates the need for a soundcard to act as a transport. Basically, this would simply require you to connect a USB cable from your computer to the DAC. This is the simplest option but also, usually, the lowest quality one. This is all IME and I may be generalizing (wrongly) here about USB vs optical/coaxial.

I've omitted some details and options for the sake of simplicity but this should give you a general idea. The answer to your question really is pretty simple.

Originally Posted by HeadphoneAddict

The eXStata is a great amp, but it was so highly detailed that we could hear jitter (grainy griity in the highs) with the Apple TV on Saturday, which at first was more difficult to pick up with the GES until 3 hours into the meet, making us have to change the transport to a Macbook Pro instead (big improvement). I posted about this in the CanJam @ RMAF impressions thread Saturday.

Although much better with a new transport, it was still a bit bright with my PS Audio Digital Link III, and more suited to the O2 Mk1. Also we think the PSA was overdriving the XLR inputs which we measured on Sunday at 5v @ 60Hz. So on Sunday (today) Bill started the day with a DIY Opus DAC, and that fixed the sound completely. At that point the amp was very good to my ears with O2 Mk1, Jade, SR-404 LE, HE60, Smegma Pros (woody Gamma pro), SR-404 LE, and SR-Lambda normal bias.

Being in a separate rig than the GES on Sunday made it more difficult to compare the amps like we did on Saturday. But on Saturday (with the same source and side by side) we felt the Woo's timbre and tone/Frequency balance was better, but the soundstage and separation was much better with the balanced eXStata (with a little more power too). With the Opus DAC the brightness/thinner sound became more balanced and punchier in the bottom end, and with even more power - enough to tickle your ear drums and make the skin on your face vibrate with O2's. I thought that wiatrob had modded the amp overnight, the improvement was so dramatic!

Today, at the end of the meet, we tried the CullenCircuits modded PS Audio which was better with the eXStata than the stock PSA, but the Opus DAC seemed to have the best synergy with it to me. I picked my PS Audio DLIII initially because it was what I needed to brighten up the dark sounding O2 Mk1 with the GES (after rolling brighter tubes). What works for the GES isn't always the best for the eXStata. I was very impressed with the eXStata by the time we had sorted out all the jitter/synergy issues with the transport and DAC. Even if nothing gets changed in the design, this amp will still be a big hit, and my understanding is there are still a few things that can be done to make it even better. The listener just needs to remember that with this amp whatever you feed it is VERY important, because it will be so resolving that you will hear any issues - for example it was fairly bad with 192k MP3 files on the Cullen modded DAC owner's PC, and we had to switch to a CD transport to evaluate the amp with the Cullen modded PSA DAC.

It's caused a dilemma for me because I was thinking I would have to sell my GES, WA6, K1000 and RS-1 for a Woo WES, and now maybe all I really need is to add an eXStata (and EHHA for K1000) to what I already own, and just sell the APS V3 RS-1 to cover the cost. :veryevil:

Originally Posted by Uncle Erik

J.S. Bach, Toccata and Fugue in D Minor. You have heard this before, by the way. It's a famous piece used in lots of media. If you like it, try the rest of Bach's organ works.

BlaineShelby, the crackling you heard might have been clipping. If an amp cannot sustain the headphones' demand for power (almost always with low notes), then it "clips" or cuts out. A fine example of why all amps are not created equal, as well.

Amps are not about power. They are about control. You might want to compare an amp to the engine of a car. True, in some ways. However, a much better analogy would be to a car's suspension.

A car handles differently depending on the road it's driven on. The same is true of music. If you're driving through a curvy road at 55MPH with terrible suspension, the car will be all over the place and might put you in the ditch. The same road at 55MPH in the same car, but with a finely tuned suspension, will be an entirely different sensation. Instead of slopping all over the road, the car feels secure and pleasurable to drive.

That is the difference between a good amp and a bad one.

There are lots and lots of technical reasons why amps sound different. Further, there are many, many different circuit designs that affect the sound.

It would take a book to go through everything, but take a look at impedance. Amps have an output impedance curve - it changes depending on how itis being driven and what is connected to the amp. Similarly, headphones have impedance, also on a curve.

Impedance tells you how efficiently power transfers from the amp to the headphones. Since that constantly varies depending on the amp and the headphones also constantly vary, you get a particular sound signature.

Yes, this is complicated, but just think about overlaying a graph on another one and looking at the differences by frequency.

This is part of the reason why two (for example) 500mW amps can sound entirely different with the same music and headphones. Each amp will have a unique output impedance curve which will interact differently with the headphones' impedance curve. That gets you a different sound from each amp.

There are a number of other factors that influence the sound of an amp, too, but I hope this example makes sense.

Also, you might run across opinions of those who say an amp makes no difference whatsoever.

That's nonsense, and demonstrably nonsense. As with the clipping you hear (probably it's clipping) you have amps with differing levels of output. Most importantly, however, is that you can measure an amp's output impedance and other relevant stats. It's not one of those "just trust us and give us money" audio deals, you can put an amp on an oscilloscope and measure it. You can directly compare two amps scientifically and demonstrate differences in repeatable tests using standard equipment.

Further, the deniers usually cite several studies where people were not able to hear a difference. Fine. Funny thing is, if you look at the rules of those tests, you will notice that they exclude certain types of amps.

Hmmmm... so to prove that all amps sound the same you can't test amps that sound different because all amps sound the same.

Does that make any sense to you?

If you want to go a step farther, there are often wide variances in the build quality of amps. Poke around here and you'll find examples of manufacturers gone horribly wrong. You'll want to make sure that whatever you buy was built correctly.