# Digital pre-amp Not DAC



## foxint (Jan 9, 2014)

Hi Guys

I have a question. You have more experience than I…..


Currently: PC output & DAC output go to a passive pre amplifier with a selection switch and stepped attenuator – XLR. DAC had only 1 input.

Then this goes to all sorts of stuff eventually to a stereo amplifier 100w. ALL XLR

Is there something called a digital pre amplifier??

I want to use the optical output of the PC (that I have stored music in FLAC - digital) and the output from the CD transport to go into something…… that I can switch between the 2 sources and also have some method of volume control. For some reason the output from the CD is louder than the output from the PC


So I am sort of looking for a digital/optical passive pre-amplifier. Does this exist??

I already have a separate DAC

Regards
Dan


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## ajinfla (May 10, 2009)

foxint said:


> Hi Guys
> Currently: PC output & DAC output go to a passive pre amplifier with a selection switch and stepped attenuator – XLR. DAC had only 1 input.
> Then this goes to all sorts of stuff eventually to a stereo amplifier 100w. ALL XLR
> Is there something called a digital pre amplifier??
> ...


Hi Dan,

Let's work backwards. For your stereo amp to receive a usable signal, it has to be analog. So the "in between device" you are looking for, must either be some form of a DAC with (analog) output volume (to receive the digital outputs of your sources)....or a purely analog preamp (where the digital to analog conversion has previously occurred)...which you already have....albeit in "passive" form.
What is unsatisfactory about your current setup? The loudness issue?
That could be cured by using an active analog pre, rather than a passive one.

cheers


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## foxint (Jan 9, 2014)

AJ

Thanks for the reply. Sorry I was not clear.

From the DAC it is all analogue. The passive pre does have volume adjustment as a stepped attenuator. The stepped attenuator adjusts the level that eventually goes to the power amp.

My issue is I want to remove the DAC in the PC and send it to my separate DAC.

So that means I have 2 optical/digital sources. The DAC has one input. 

I need a box/something to connect the PC digital out and the CD transport digital out. It needs a switch so I can select PC or CD and volume adjustment so I can control the volume as the CD is far louder than the PC digital.

Dan


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## Wayne A. Pflughaupt (Apr 13, 2006)

foxint said:


> I want to use the optical output of the PC (that I have stored music in FLAC - digital) and the output from the CD transport to go into something…… that I can switch between the 2 sources and also have some method of volume control. For some reason the output from the CD is louder than the output from the PC


What you’re describing is a basic – read common – pre-amp. Just about all of them these days accept digital inputs. Seems painfully obvious, so maybe I’m missing something? 

As far as I can see, your separate DAC is redundant. The pre-amp can do that.




> So I am sort of looking for a digital/optical passive pre-amplifier. Does this exist??


It’s electronically impossible to have a passive pre amp that accepts optical inputs.

Regards, 
Wayne


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## foxint (Jan 9, 2014)

Hi Wayne

Thanks for the reply.

•	My pre-amp only has XLR inputs and uses a stepped attenuator. It was quite expensive, so while it may have to go, it is audiophile quality but only accept XLR and analogue inputs.
•	So no my pre-amp cannot do what a DAC can do
•	My separate DAC is relatively new and I would rather like to keep it.

I am not looking for a passive pre-amp, as I already have one. Perhaps my terminology is not right.

I am looking for a box (for want of a better word) to accept 2 optical/digital inputs that has a switching mechanism (manual or electronic) and a volume adjustment mechanism,

Sorry for being so unclear

Dan


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## Wayne A. Pflughaupt (Apr 13, 2006)

foxint said:


> I am not looking for a passive pre-amp, as I already have one.


I wasn’t speaking of a passive pre-amp, but the more-common active type. Sorry if that wasn’t clear. 

Any active pre-amp can do what you’re describing:


> I am looking for a box... to accept 2 optical/digital inputs that has a switching mechanism (manual or electronic) and a volume adjustment mechanism,



It sounds like you want to dump both the computer and CD transport to a switching device that will then feed your DAC, which in turn will be fed to an input to your analog pre amp? If that’s the case, then  something like this is probably the best you’re going to be able to do. You aren’t going to find a pass-through device of this type that will do digital-domain volume adjustment – at least not in any consumer-product line. There's just no demand for such a product when any common AVR can do all that. And I expect that any professional-grade hardware solution that might be available will cost way more than you want to spend.

I can understand your desire to keep your current pre-amp, but if it only accepts analog inputs and all your sources are digital-output only (or it’s your desire to only use the same), then it obviously isn’t meeting your needs. I apologize if this sounds blunt or harsh, but it seems to me you should either change out your source components to some that are compatible with your pre-amp – i.e. analog components with XLR outputs - or get a pre-amp that’s compatible with your source components.

As a bonus with the latter option, it shouldn’t be hard to find a pre-amp that has a trim adjustment for the inputs, to solve your volume mismatch issue.

Regards, 
Wayne


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## foxint (Jan 9, 2014)

Hi Wayne

Thanks for the reply. Yes 

“Dump both the computer and CD transport to a switching device that will then feed your DAC”

The link to the “Optical Toslink 3 Input Selector Switch” looks like it performs the switching function that I want. 

Hoping for a more aesthetic solution: all my equipment is 19 inch rack mount black and some brushed aluminium. Any suggestions?

So what you are really saying is replace the DAC with a DAC with more than one input and XLR outputs.

Thanks for the advice. I will keep looking.

Dan


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## ajinfla (May 10, 2009)

Hi Dan,

It seems you may have cornered yourself a bit with these "audiophile" components. A DAC with only one input??
It would be really, really helpful if you gave specific brand/models. Does your CD player have a coax (rca) digital out (or is it an "audiophile" model too)?
If so, you could feed that and the PC optical to one of these http://www.behringer.com/EN/Products/SRC2496.aspx, then feed the optical out to the in on you DAC.
Maybe cover the "Behringer" logo? 

cheers


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## foxint (Jan 9, 2014)

Hi AJ

Ha-ha…. I know Behringer has its critics. But is it that bad????

I have been thinking and you guys have been great….

I was getting confused with the DAC Output that is only XLR. Everything now is XLR.

The DAC input has: a Tosh link; USB; and BNC.
CD Transport output has: Tosh link; BNC

When I ordered the DAC & CD Transport I optioned it for no RCA. Little Dot is the brand from the land of everything – China.

Yes the light has just been turned on…. I can attach the PC via the USB and the CD via the Tosh link.

I was a little too focused on the purity of the optical output. 

I am truly an idiot. Sorry for wasting your time

I think the USB will bypass the PC sound altogether?? Not really sure where BNC fits in to the equation, but I do not think I have any…

Thanks guys….

Dan


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## ajinfla (May 10, 2009)

foxint said:


> Ha-ha…. I know Behringer has its critics. But is it that bad????
> 
> Yes the light has just been turned on…. I can attach the PC via the USB and the CD via the Tosh link.
> 
> ...


Hi Dan,

Some B products are junk, others are excellent and superb values. They make a lot of stuff!

Yes, that should do it. I was beginning to wonder about audiophile sanity with a one input DAC in 2014....

No problem or time wasted. All questions are good. Many others reading, other lights may go on too.

Yes, USB connection leaves "DA" conversion to DAC. That should also cure your level difference issues.

cheers


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## foxint (Jan 9, 2014)

Guys

Thank you all.

It is an interesting journey of discovery....ha-ha.

Dan


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