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Whats the difference between using line in and usb from a portable dac/amp combo to a...

post #1 of 5
Thread Starter 

I've heard using usb doesn't give a 100% pure signal. Is this true? 

post #2 of 5

Depending on what unit you are talking about a line in typically refers to the amp section only.  Take the Bithead from HeadRoom for example.  The line in is designed to take the analog output from a device and run it through the amp section of the Bithead completely removing the DAC from the equation.  If you are talking about the XLR or RCA line in then this is yet again an analog only signal.

 

A typical signal chain would be PC ---> DAC via USB ---> Amp via RCA ---> Headphones via headphone out.

 

To me USB is one of the methods to achieve an extremely good signal especially if an asynchronous DAC is used.  The clocking is difficult to improve upon.

 

To me the signal is not about purity as much as whether or not you want your DAC/Amp to do the Digital to Analog processing or some other device.  If you have a different DAC or something you prefer to listen to then the line out from that device would be preferred because you remove the DAC on the DAC/Amp combo.

post #3 of 5
Thread Starter 

So if I used a portable dac/amp such as the alo audio international or the pico dac/amp to connect to a computer via usb, it would only function to bypass the internal dac section of the computer, not the amp section as well? So essentially I would be using the inferior internal amp of my computer to amplifying the analog signal converted by the superior portable dac? 

 

If this is true, then how is it that the centrance dacport is able use it's own internal dac and amp via usb without having the need to connect an additional XLR or RCA cable for the dac section? By the way, what do you mean by using an asynchronous dac? 

post #4 of 5
It would go like this

PC digital signal through USB > International DAC (digital becomes analog) > International AMP > Headphones.

This way, your PC DAC and amplifier are out the equation. Using USB, your PC sound card doesn't even get to "mess" with the signal, digital or analog.

Also a Digital signal doesn't get amplified this way, only after it has been converted to analog that it needs an amplifier.
Edited by Kiont - 4/27/13 at 10:18pm
post #5 of 5
Quote:
Originally Posted by Fungus View Post

So if I used a portable dac/amp such as the alo audio international or the pico dac/amp to connect to a computer via usb, it would only function to bypass the internal dac section of the computer, not the amp section as well? So essentially I would be using the inferior internal amp of my computer to amplifying the analog signal converted by the superior portable dac? 

 

If this is true, then how is it that the centrance dacport is able use it's own internal dac and amp via usb without having the need to connect an additional XLR or RCA cable for the dac section? By the way, what do you mean by using an asynchronous dac? 

 

A combo device like that uses the USB signal from your PC to feed its own internal DAC and then also internally amplify the signal.  You would remove a ton of noise and other audible problems from the audio chain by doing this, but there will always be some processing done by the PC.  To me listening to audio from a PC via USB is one of the best ways to listen to it.  The process has some so far over the last 10 years.  The primary amp inside your PC would be bypassed.

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