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O2 AMP + ODAC - Page 284

post #4246 of 4251
Quote:
Originally Posted by DIscoYou View Post
 

With the Epiphany Acoustics O2Di (Amp & DAC) does anyone know how the headphone and DAC outs switch? Is it a case of the RCAs only being live when there are no headphones plugged in?

 

http://epiphany-acoustics.co.uk/products-page/dacs/ehp-o2di-desktop-headphone-amplifierdac-3/


Anyone?

post #4247 of 4251
Quote:
Originally Posted by DIscoYou View Post
 


Anyone?

 

It might be better to send them an email about it.

Also it would be better if they added that on the product description page.

post #4248 of 4251

Hi, I asked this question some time ago to Oliver from Epiphany Acoustic, who replied as follows:

 

"the RCAs on the back will output the line level input direct from the DAC so you would connect that to your pre amp as you say.

 

The only little thing to mention, which won't affect usability, is that the DAC can only support one output at a time (the internal headphone amp or the RCA line out) and there is no internal switching mechanism.

 

As such, you simply have to either power off the pre amp if using the headphones or power off the O2Di if using the speaker system. The DAC gets it's power via USB so will always be on regardless of when the red light on the O2Di is on or off."

 

Hope it helps.


Edited by blacknile - 4/24/15 at 8:40am
post #4249 of 4251
Quote:
Originally Posted by blacknile View Post
 

Hi, I asked this question some time ago to Oliver from Epiphany Acoustic, who replied as follows:

 

"the RCAs on the back will output the line level input direct from the DAC so you would connect that to your pre amp as you say.

 

The only little thing to mention, which won't affect usability, is that the DAC can only support one output at a time (the internal headphone amp or the RCA line out) and there is no internal switching mechanism.

 

As such, you simply have to either power off the pre amp if using the headphones or power off the O2Di if using the speaker system. The DAC gets it's power via USB so will always be on regardless of when the red light on the O2Di is on or off."

 

Hope it helps.

 

That's very informative, thanks.

 

It is interesting that the DAC is USB powered. Isn't the amount of power available to a USB device lower than the amount of power that a line level output can need? (I think it was a Z review where I saw him mention that).

post #4250 of 4251
Quote:
Originally Posted by DIscoYou View Post
 
Quote:
Originally Posted by blacknile View Post
 

Hi, I asked this question some time ago to Oliver from Epiphany Acoustic, who replied as follows:

 

"the RCAs on the back will output the line level input direct from the DAC so you would connect that to your pre amp as you say.

 

The only little thing to mention, which won't affect usability, is that the DAC can only support one output at a time (the internal headphone amp or the RCA line out) and there is no internal switching mechanism.

 

As such, you simply have to either power off the pre amp if using the headphones or power off the O2Di if using the speaker system. The DAC gets it's power via USB so will always be on regardless of when the red light on the O2Di is on or off."

 

Hope it helps.

 

That's very informative, thanks.

 

It is interesting that the DAC is USB powered. Isn't the amount of power available to a USB device lower than the amount of power that a line level output can need? (I think it was a Z review where I saw him mention that).


usb is 5V, a DAC is supposed to output something like 2V into several thousand ohm of an amp input, so the current requirement is ludicrously small and so is the power.

now for stuff with DAC and amp both powered by USB, I might not make the same comment, because an amp may need real power ^_^.

post #4251 of 4251
Quote:
Originally Posted by castleofargh View Post
 


usb is 5V, a DAC is supposed to output something like 2V into several thousand ohm of an amp input, so the current requirement is ludicrously small and so is the power.

now for stuff with DAC and amp both powered by USB, I might not make the same comment, because an amp may need real power ^_^.

 

Correct, and most USB ports can supply up to at least 500 mA (most modern ones can do more). This is a couple of watts, and so is plenty for most "normal power" headphone amps.

 

The voltage also isn't a limitation per-se; many USB DACs use tiny power switchers that convert the +5V USB power into +/- 5V (or even higher voltages) for driving their audio circuitry. Some of the headphone amplifier chips commonly used by USB DACs even have this capability built right in (so they can deliver an output signal up to almost +/- 5V even when running from a single +5V supply.

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