Other than what Judd suggested - you may also want to try the ERC-2 directly to the USP-1 via RCA (keeping the XDA out of the loop). Some seem to prefer it direct, so using the ERC-2's conversion to analog instead of the XDA's.
Lots of options to test. Then see which one you like. It may not be the same as what others prefer. Go with what suits your ears, room, and source content the best.
That's the beauty of it all, or the scourge, depending on your patience and discernment.
Yes, I havent been able to hear a difference between usb or toslink optical. But some people on this forum claim that they do. Having not had a VERY high end system to try it out, I couldn't tell you for sure, but I doubt you will hear an audible difference between any of the connections. Something that would affect the sound more, make sure that your itunes is outputting BIT PERFECT audio via your digital out. There are various add-ons that you can use to make itunes do this. I just don't know much about macs so I think other people can advice you more on this.
You can try other options but I think your best option (and the designer of the emotiva products confirmed this) is to make sure everything is connected to your USP-1 in the end. So, therefore, your XDA-1 will be connected to the USP-1 and so will your ERC-2. Depending on which device you want to be your DAC you can connect the ERC-2 to the XDA-1 (hint both have AES/EBU capabilities if you want to get all fancy ) making the XDA-1 your DAC. Then the XDA-1 will connect to the USP-1. I hope you know what a DAC is, if not, do feel free to ask. But it is an important part of your audio chain.
The other alternative is to connect the ERC-2 directly to the USP-1 making the ERC-2 your DAC. Find out which sounds best for you.
Either way, if the XDA-1 is connected to the USP-1, make sure the volume on the XDA-1 is set to 80.0, this bypasses the volume control on the XDA-1. The XDA-1 volume control has a less than ideal way of adjusting the volume where it cuts off the "bits" to reduce the volume so technically you lose information as you reduce the volume. For some people it may be audible, for others it is not. For me, even though it is barely audible, I always get the feeling that the music is noticeably BETTER when it's louder. I attribute this effect to the XDA-1 volume control as I didn't have this issue on other equipment. When you set the XDA-1 to 80.0 there is no cutting off bits and it functions as a DAC bypassing its volume control. The USP-1, has no such problem at low volumes. So by putting the volume on the XDA-1 to 80.0 and using the USP-1 for volume, then you bypass this whole issue. Also, make sure your itunes volume control is set to maximum. (In short, only the USP-1 should be adjusting the volume). And turn off any software equalization you might have going on (like sci-fi setting, jazz setting, room setting or dynamic range settings like quiet, medium or loud volume). You want everything set to be as flat as possible and for the dynamic range to be unrestricted. Lastly, if you can't hear a difference between the ERC-2 and the XDA-1 DACS or prefer the XDA-1 sound, then the ERC-2 may not be NECESSARY for your system depending on your needs. Because if you hook any cheap 30 dollar cd or dvd player up digitally to the XDA-1, you can acheive that same great sound quality of the ERC-2 connected digitally to the XDA-1. (This is true). You can also rip your CD's onto your computer via FLAC losseless files and get the EXACT same quality. All this depends on if you don't find an audible difference between the XDA-1 and the ERC-2 DACS. If so, you can actually take advantage of your 30 day money back period and return the ERC-2 and just use the XDA-1 and the USP-1. But of course, that's completely up to you. Hope that helps. Enjoy the music, you have a fine set of equipment. What speakers are you going to be running?
I will be running Focal Chorus 836v speakers and B&W ASW675 sub with this system, only for stereo. Anyway i thought that having a separate DAC would be better than using the ones on the cd player or the iMac. And i prefer having a conventional volume knob rather than up down push buttonslike the ones on the XDA-1. Connecting the XDA-1 to the iMac via USB would that automatically by-pass the iMac's DACs and use the XDA-1's DACs or i have to do some modifications?
Yes sir! Connecting your CD player or imac to the XDA-1 completely bypasses your computer and CD player DACS hence why I was saying that your cheap 30 dollar CD player hooked up to the XDA-1 should sound very similar to the ERC-2 hooked up to the XDA-1. (The ERC-2 uses identical DACS as the XDA-1 but that doesn't necessarily GUARANTEE that it sounds the same). If the ERC-2's analog output sounds similar or identical to your ears to the XDA-1 analog output via USP-1, then you save quite a bit of money returning the ERC-2 I'm not saying the ERC-2 isn't a fantastic product, but that you may achieve something very similar (or identical) using an XDA-1 and a very cheap CD or DVD player. It's upto you, your needs, preferences, and your ears though
Only thing to pay attention to on the PC or mac side is to make sure you are getting BIT PERFECT output. Computers operating systems have a funny way of messing with the audio stream. Other people would be able to help you regarding this issue.
Well, the problem is the fact even if output is bit perfect (i.e. the digital data itself remains fully untouched throughout the entire output path that it travels through) you still cannot guarantee anything whatsoever about what's going to happen to it after that. I mean, the data has to be sent into the Digital to Analog Converter (DAC) chip. This means that timing issues might occur, because the digital data has to keep flowing at a constant rate and never be interrupted even the shortest period of time if you want to obtain the perfect accuracy from the chip. But that's only theory. In practice, all DACs have timing issues. The clock that controls the data rate is never accurate. So in the real world, a digital data stream is always a jittery one. Most DACs use some kind of jitter cleanup mechanism but the performance of this mechanism still depends on all kinds of things. For example, if using S/PDIF, the accuracy of the clock that's inside the S/PDIF receiver matters but the clock that's inside the S/PDIF transmitter also matters. A power supply's ability to deliver clean power signals will also have an impact on clock accuracy. Electric noise might travel through a coaxial S/PDIF cable and still mess up the sound. Using an optical S/PDIF cable does not always help either, because the same electric noise might still mess up the clock in the transmitter and because optocouplers tend to slowly degrade over time. Things are not quite as simple as they might appear.
Well, the problem is the fact even if output is bit perfect (i.e. the digital data itself remains fully untouched throughout the entire output path that it travels through) you still cannot guarantee anything whatsoever about what's going to happen to it after that. I mean, the data has to be sent into the Digital to Analog Converter (DAC) chip. This means that timing issues might occur, because the digital data has to keep flowing at a constant rate and never be interrupted even the shortest period of time if you want to obtain the perfect accuracy from the chip. But that's only theory. In practice, all DACs have timing issues. The clock that controls the data rate is never accurate. So in the real world, a digital data stream is always a jittery one. Most DACs use some kind of jitter cleanup mechanism but the performance of this mechanism still depends on all kinds of things. For example, if using S/PDIF, the accuracy of the clock that's inside the S/PDIF receiver matters but the clock that's inside the S/PDIF transmitter also matters. A power supply's ability to deliver clean power signals will also have an impact on clock accuracy. Electric noise might travel through a coaxial S/PDIF cable and still mess up the sound. Using an optical S/PDIF cable does not always help either, because the same electric noise might still mess up the clock in the transmitter and because optocouplers tend to slowly degrade over time. Things are not quite as simple as they might appear.
Thanks for the input,
So basically what I understood is that it's better to use the DAC in the cd player rather than send the data to the component stand alone DAC because transferring the data through the coax or S/PDIF can affect the quality even more, specially if the both DACs are similar in specs. Is my understanding accurate?
Not quite. Typically a CD player's DAC is a compromise along with all the other gear in the box, whereas a standalone unit is going to have that as its focus. So you want to let the CD player do the CD playing (transport bits) and the DAC doing the DACing.
If you have the same DAC, it shouldn't matter. Jitter in good equipment is not the issue it's blown up to be.
When it comes to a source like a computer you absolutely want to use your external DAC because the one in your sound card is cheap and surrounded by noisy electronics. If you're doing that, you might as well take a digital signal from you CD player as well.
One more thing on the cabling. In most situations there is little to no difference between optical and coax. However, over long runs, Toslink is preferable. On the other hand, if the cable has sharp bends then coax is the better choice.
It depends. Some CD players have an excellent in-built DAC, some don't. Using a standalone DAC does not necessarily warrant better sound. Also, I do not believe the jitter problem is overestimated. To use an extreme example, if you plug an Antelope Zodiac Gold 384 directly into the S/PDIF output of a computer motherboard then it just might sound worse than if you connect the same motherboard to an XDA-1 using an Audiophilleo2. So you need to find the weakest link, which is something that usually cannot be achieved by just looking at specs and measurements alone. Measurements are only an indication, they do not warrant good sound at all. Audio is part science, part subjective. There simply are no objective answers as to which sounds better.
Yves, yes, I feel that it is better to rely on subjective hearing because even though measurements are very very useful, and I usually rely greatly on them, I don't think we can accurately use them to identify how that translates to good or improved sound in every case, especially the subtle ones. But having said that, I don't think jitter has as much to do with impacting sound reproduction. I would venture to say it doesn't have an audible difference, but keep in mind that I don't have enough experience with a proper high end transport or truly high end speakers and equipment. So, I'm not saying it's impossible, but just not as likely. I have tried to differentiate between my HD-DVD player on CD's via toslink and FLAC losseless via USB out and it's sounded the same. However, I tried the ps3 CD player via digital and it wasn't very good, and I think that has something to do with an additional conversion step the ps3 MAY be using in its signal processing path thereby negating bit perfect output.
Bezdikjack, since you have the benefit of having both, why don't you try the two and tell us if there is a difference and what you noticed (ERC-1 to XDA-1 to USP-1, ERC-1 to USP-1, and finally your cheaper CD player to the XDA-1). You don't even have to unhook anything, because the USP-1 will accept both the ERC-1 input and the XDA-1 input. Just make sure the XDA-1 volume is set to 80. I don't need extensive double blind testing, just your subjective impressions.
Garbulky, less than two years ago I also didn't believe transport jitter could seriously mess up the sound. I just thought bit perfect playback was enough. Now that I finally have my stereo system that I've been dreaming about for 12 long years, my whole world's turned upside down. With 24-bit 192 kHz FLAC files, the soundstage is as big as a house and the holographic imaging is almost as real as that of a live performance. Compared to an audio CD, it's a night and day difference. In fact, on a CD everything just sounds lifeless and utterly fake. And no, it's not a flaw in my stereo system that's causing this because I can very clearly hear the exact same effects on any very high end stereo system. But when I hook up my DAC through the cheap onboard S/PDIF of a computer motherboard then the magic of Hi Res music files also disappears. The three-dimensionality and separation just falls apart almost completely and the deep bottom end starts to sound all muddy so that I can barely hear the impact of drumsticks anymore and the beautiful detail gets drowned as if someone is smearing mayonnaise onto my window. This is why I fell in love with my XPA-2 amp, when combined with a good DAC and a pair of really excellent floorstanding speakers it brings the music to life. It's all about the amazing realism. It's the experience of truly "being there". I have absolutely no idea how else I could describe it.
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) making the XDA-1 your DAC. Then the XDA-1 will connect to the USP-1. ![[avatar]](http://img580.imageshack.us/img580/6096/sinatra.png "[avatar]")