Hi Aiden,

You can check the manual on page 62.
https://www.rme-audio.de/downloads/adi2dac_e.pdf

Do you see what I deal with Aiden? 

Experiment a bit.  RME will allow this!

Enjoy!

BTW, if you use Bass/Treble, PEQ and/or dynamic loudness, then this has also impact on the reference level to stay in an optimal range.

I think you know already about the "Auto Reflevel" feature that automatically chooses the proper reference level for the RME DAC according to
a) what output level you dial in at the front and
b) in dependency of B/T, PEQ, LD settings

Usefullness of RME "Auto Ref Level" feature

Now the nice thing is, that you can use this "Auto Ref Level" feature of RME DACs to create an Excel sheet for finding out:

• optimum reference level, no matter whether you use fix settings or Auto Ref level

• optimum reference and volume level settings with the aim to maximize SNR for both devices, the RME DAC and the connected HiFi Preamp / Amp, that is connected behind it

For the 2nd use case you only need to know the maximum V (eff) that is allowed on its balanced or non-balanced inputs. It needed a day but my HiFi dealer was able to deliver this information for my Accuphase E-600 Class A Amp from PIA in Germany. Be prepared that some HiFi shops might not understand the purpose and you need to explain that you want to maximize SNR of both devices in your setup

Here is how I created such an EXCEL "cheat sheet" for my setup to find this out...

Things that you need to know to create the Excel sheet:
- Ref levels of RME DAC: ADI-2 Pro FS R BE: +24 dBu at 0dB volume and +19, +13, +4 dBU
- Balanced input of Accuphase E-600 amplifier: max 2,5 V max. allowed

On the ADI-2 DAC/Pro its helpful to map a key on the front to be able to quickly "toggle" (enable/disable)
B/T, PEQ and dyn. loudness:

• ADI-2 PRO*: "EQ" -> "EQ+B/T+Ld 1-4"

• ADI-2 DAC*: "EQ" -> "EQ+B/T+Ld"

1. My Excel starts ..

... with two columns with dBu and the calculated V (eff) according to Sengpiel formula:
http://www.sengpielaudio.com/Rechner-db-volt.htm

Excel Cell "A16" contains the dBu value from which we calculate V (eff).
German Excel, dBU to Volt (eff):  "=0,7746*POTENZ(10;A16/20)"
English  Excel, dBU to Volt (eff):  "=0,7746*POWER(10;A16/20)"

I started with at 24 dBu in 0,5 dBu decrements (because +24 dBu is the maximum ref level of the ADI-2 Pro at 0dB volume.

From the technical data section of the manual I know, that my ADI-2 Pro FS R BE has this max SNR depending on Ref Level:
- Signal to Noise ratio (SNR) @ +13/19/24 dBu: 120 dB RMS unweighted, 124 dBA
- Signal to Noise ratio (SNR) @ +4 dBu: 117 dB RMS unweighted, 120 dBA

So the 1st lines that you get in this Excel are:

dBu    Volt (eff)  Volume    SNR @+24 dBu Ref Level
24      12,28       0            120
23,5      11,59       -0,5        119,5
23      10,94       -1           119
22,5      10,33       -1,5        118,5
22        9,75       -2           118

2. Add additional colums for the different Ref Levels

Disable "B/T, PEQ, LD" best by using the remapped key, as this is the easiest to ensure quickly neutral settings.
Then look where the Reference Level changes in the display of your DAC.
By this you can easily fill the excel sheet for all four Reference Levels and the resulting SNR in dependency of the volume that you dial in with the volume knob of your DAC.

Then the Excel will look like this...
Do not become confused about the additional columns right from Col H, these are the interesting values should you e.g. use a permanent Bass boost of +3 dB like I do, then you need to reserve some headroom in the volume / reflevel selection.

This is the final Excel for me, if you want to use it as a start for you:
https://www.dropbox.com/s/2qrh9mzmcv3yb … .xlsx?dl=1

From this Exel I learned now 2 things:

For the Accuphase with fix Ref Level setting its clear, this device gets its maximum SNR at max 2,5 V on its input.

How to use the Excel now:

The objective is now to lookup in the Excel, where I get the best Volume Level and Reference Level for optimum SNR.
I prefer to leave auto reflevel on here

1. for neutral settings (without +3 dB Bass boost):
With Auto Reflevel enabled: at volume -14 which automatically chooses the proper ref level +13 dBu -> 117 dB SNR

2. with my +3 dB Bass Boost enabled
With Auto Reflevel enabled: at volume -14 which automatically chooses the proper ref level +13 dBu -> 117 dB SNR

Fix Ref levels
I leave it up as an exercise for you to get the proper volume / ref level when using fix reference levels

RME example from manual
This Excel also helps to maybe easier understand the information in the RME manual. There is a chapter in the RME manual which demonstrates that choosing the proper Ref level results in lower SNR ... https://www.rme-audio.de/download/adi2profsr_e.pdf, see ch. 21.3

Conclusion
The RME Auto Ref Level feature is so extremely useful for operation and even supports you to create such an Excel with ease. In this case the +3 dB Bass increase was an easy example. When using more complex B/T, PEQ, LD settings you get a great help to see how this impacts the proper ref level to be chosen on the unit.

BTW .. This is the result after a couple of hours scratching my head I hope I did no stupid mistake, feel free to discuss or to correct me. And .. no warranty

Many thanks you're welcome, nice that you enjoyed it, aidenyoung.

If this amp supports only one ref level like mine on its balanced inputs, then it sounds reasonable to me, that this amp gets the full SNR of 97 dB at 6.325 V. But well .. I can't comment to 100% as I do not know whether this data is accurate

So if you would own the ADI-2 Pro FS R BE, then you could use the following settings with auto ref level enabled:
DAC Volume: -6
By "auto ref level" feature the a Ref Level of +19 dBu would automatically be chose, you see it on the front display
and finally you should achieve then a SNR of 119dB at the ADI-2 Pro FS R BE.

If you would use fix levels, then you would need to
- disable "auto ref level"
- configure a fix Ref Level of +19 dBu
- set volume to -1
to get the 119 dB SNR.

But even if you would use a fix reflevel of +24 dBu and use a volume of -6 then you would still have a SNR of 114 which is much higher compared SNR on your Amps input.

I hope I made no stupid mistake LOL .. that was also kind of "new land" for me to perform the settings up to this detail.

Curt, quick question, how can you know that these are unbalanced RCA plugs?

I searched through all of his postings and didn't find any statement in terms of, what integrated amp he has and what inputs this amp supports: whether balanced or unbalanced and which inputs he choosed now for connecting the RME DAC.

My integrated amp also has both, balanced and unbalanced inputs.

We only know up to now that the inputs might support 6.325V where its unclear to me whether this is a RMS or a peak level.

@aidenyoung: could you kindly detail which integrated amp you use and to what input you intend to connect your ADI ?
Do you connect the ADI to the preamp section of your integrated amplifier or is there a special input to the power amp any you want to use the ADI as preamp in the integrated amp ?

Absolutely, let me briefly tell you guys what gears I am currently connecting to the RME ADI-2 DAC. The integrated amp I am using is the Accustic Arts power 1 mk4, and the ADI dac is connected to the balanced input of the amp. So, the spec I provided previously was straight from the user menu. Therefore, it didn’t really mention about whether it is refer to unbalanced or balanced input.

So the 6.325V is the peak level of the balanced input I presume? Does it indeed a very high input level? Coz I knew this integrated amp is pretty powerful and I used it to drive a pair of 805D3.

The setting I had used before is to set auto ref and select +7dbU and then the dac volume was set at -10db, I basically just leave it as it is and I mainly control the volume from the integrated amp instead. So in this case if I use auto ref I basically can go as high as +13dbU (balanced +19dbU) and volume can be -6db? Sometimes I’m afraid if I turn it too high it will do damage to the speaker. That’s why I’m curious whether I should use turn on auto ref or not.

Pardon me but I tried to reread the posts above multiple times and the subject is vague and confusing to me, after visiting sengpielaudio I got 17.78 dBu. I am using +7 dBu fixed level which is +13 dBu XLR, I am afraid to use the maximum fixed level, My amp XLR input maximum sensitivity is 6 Vrms, what would be the optimum settings from ADI-2 DAC side, thanks & best regards!

As a preambule, you won't damage your amplifier or your speaker if you feed it a little too hot: you will hear distorded sound and it would be the time to lower the volume on the DAC.

And if you feed your amplifier too low by a few volt, no drama here neither: like Curt said, if you don't hear noise or "hiss", you are fine!

Will you plan to use bass/treble controls of the ADI or its EQ ? If not, set a fixed level of +19 dBu, volume at -1dBr, lock it and you are fine (6,15 V RMS < 6,325 V RMS).
If you plan to use B/T or EQ on the ADI, lower the volume on the DAC: if you sometimes use +3 dB bass boost for instance, set the volume to -4 dBr (-1-3 = -4): you will have the necessary headroom.

It's really not rocket science: just common sense.

It's just a shame the amplifier maker doesn't clearly indicate the sensitivity of the inputs, it would be easier to advise you...

Hi Arnold, what amp do you have ?
I do not see any values for your pre-amps balanced line level inputs.
Please find out whats the highest V (RMS) that the balanced inputs of your preamp support.

HI, I think this one Ramses:

Maximum Input Signal
Phono:
50mV
High Level:
5V Unbalanced
5V Balanced

Thank you

Thank you Sir, will try this and report back...

Regards,
Arnold

Hi Arnold,
If you don't use DSP functions (EQ, B/T etc.) you can leave it at 0 dB: intersample peaks can provoke overs, but the unit has headroom for those.

https://forum.rme-audio.de/viewtopic.ph … 15#p135615

The new ADI-2 DAC/Pro have even more headroom for those.

https://forum.rme-audio.de/viewtopic.ph … 49#p148949

Hi ramses, I have been playing with different setting for awhile. One thing I wanna know is I remembered you mentioned the excel chart that you created, the figures are base on Auto Ref is set to On. Let say if I set auto ref to Off, what is the reason why to set the DAC volume to 0db or -1.0db than other higher or lower dB?

I have done experiment base on your chart and set Auto Ref Off, +7dbU (equivalents +13dbU for XLR) and DAC volume -11.0 dB. Then I compare to the same setting with Auto Ref On, I seem cannot tell the different between with On and Off interchange; maybe I’m still a newbie and don’t have a good ear haha. 

Then I go back to Auto Ref off with same setting and set the DAC volume to -1.0db. But now I’m not sure how high is the SNR is if I use this setting?  Or base on my amp eff ref, I should of push it much higher like over at lease 5V shouldnt be an issue?

If you have the ADi-2 DAC then you need to create an excel of your own, as the DAC version has lower output levels and even lower on the cinch outputs, see technical data section of the manual.

I personally use auto reflevel, because then the ADI can calculate itself when its about time to switch to the next higher or lower reference level not to overload its output and to get best SNR.

See and try to understand ch 21.3 and that there is a dependency between dBu / Volt
https://www.rme-audio.de/download/adi2profsr_d.pdf
https://www.rme-audio.de/download/adi2profsr_e.pdf

With the Gain knob at the end you select a certain a dBu value..

Depending on the chosen reference level 0dB has a certain dBu/V value .. see excel, technical data section of the manual.

And you do not need to "overshoot" ... keep simply a few dB headroom, so that you can still operate Bass/Treble or PEQ without havning to adjust the level.. A few dB less do not kill the sound .. its enough of dynamics left.

I am trying to figure out the Maximum Input Signal of my tube amp (Unsion Research Sinfonia)  - unbalanced input.
The only information I found in the specs was this.

Type: Dual mono Stereo Integrated Valve Amplifier
Output Stage: single ended parallel ultraliner A class
Output Power: 25W
Input Impedance: 47 kOhm
Feedback factor: 14dB
Frequency Response: 20 – 30000 Hz

Is there anyway to calculate this value from this information?
Otherwise I would contact Unison Research.