RME ADI-2 Pro DAC Question Regarding Unbalanced Analog Inputs

[Robonaut]

Hi, all.

I have a RME ADI-2 Pro on the way (really looking forward to the upgrade!).

My SACD player (a Marantz SA8001) on has unbalanced outputs. The RME, though, only has balanced analog inputs.

In the manual it says:

When using unbalanced cables with the XLR inputs, pin 3 of the XLR jack should be connected to ground. Otherwise noise may occur, caused by the unconnected negative input of the balanced input.

I understand what it's warning me about, but I don't quite understand what I should be doing to address it. Is there some kind of special RCA to XLR cable I should be using, or something?

 

[fabriciom]

forum.rme-audio.de

 

[linuxfan]

Is there some kind of special RCA to XLR cable I should be using?

Yes. These are typically available from home recording equipment retailers ... but wait, are you intending to connect the analogue outputs of your SACD player to the analogue inputs of your ADI-2 Pro?
If so, you do realise that there will now be two D/A converters in your signal chain - the SA8001's internal DAC + the ADI-2 Pro DAC? Your signal path is now digital-to-analogue-to-digital-to-analogue !

But if your intention is to use the ADI2-Pro instead of the SA8001's internal DAC, you must use a digital output from the SA8001, which is available in the form of coaxial or optical s/pdif.
And I should warn you that only PCM digital outputs are available here, not DSD. It's extremely difficult to get DSD digital output from an optical disc player. You can read about it here -
https://www.audiosciencereview.com/...mi-audio-to-usb-conversion.11481/#post-328929

 

[Robonaut]

Yes. These are typically available from home recording equipment retailers ...

Okay. I already have good quality XLR to RCA cables from Hosa. Should that be all I need?

...but wait, are you intending to connect the analogue outputs of your SACD player to the analogue inputs of your ADI-2 Pro?
If so, you do realise that there will now be two D/A converters in your signal chain - the SA8001's internal DAC + the ADI-2 Pro DAC? Your signal path is now digital-to-analogue-to-digital-to-analogue !

I would only be using the SA8001 for SACDs. I realize that I would be doing two rounds of digital-to-analog conversion, but shouldn't that still give me better sound quality than using the digital out of the SA8001, since that would be limited to 16 bit, 44.1 khz?

 

[linuxfan]

"Two rounds of digital to analogue conversion"?
I'm out.

 

[Grotti]

For what I understand, there is no digital output when playing SACD (just read the manual of the 8001 online). So you will have to use analog connection.

I use an RCA to TRS adapter to connect my phono preamp to the RME pro: works perfectly.

 

[rdenney]

Any XLR-RCA adapter will ground Pin 3. I'm doing that with my Benchmark ADC, with no issues. Of course, a system is only as quiet as its quietest component, but I'm not picking up any noise that I can detect from unbalanced interconnects. I use the same adapters for going in and out of my Yamaha PEQ, which was designed for commercial systems back in the 90's. To go fully balanced, I would need a full-featured active preamplifier with balanced ins and outs, at least for the amp outputs, tape loops and processor loop. I have not sought that out, and don't think I'm paying too high a price for that.

Look at the back panel, the connectors also accept 1/4" phone plugs on the inputs. If you use tip-sleeve (unbalanced two-conductor) rather than tip-ring-sleeve, the sleeve will effectively ground Pin 3 for you. So, a 1/4" phone to RCA cable would be the simplest solution.

Rick "noting that not all balanced connections will tolerate grounding Pin 3, but you have the manufacturer's approval already" Denney

 

[Veri]

Any XLR-RCA adapter will ground Pin 3.

Yep. Most cheap XLR-RCA cables like the monoprice kind should also terminate like that, though.

 

[Robonaut]

"Two rounds of digital to analogue conversion"?
I'm out.

My apologies if I used incorrect terminology (I'm no engineer).

The point I was trying to make is that my setup would be this:

(1) The SA8001 converts the DSD data on an SACD to analogue output
(2) The RME converts that analogue input from the SA8001 to PCM
(3) The RME then converts that PCM back to analogue to send out to the speakers.

Steps 1 & 2 are the two "rounds" of digital to analogue conversion I was referring to.