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RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → ADI-2 Pro FS to Headphone Amp, what is the optimal output setting?
Hello,
According to the manual from SPL the Phonitor 2 has a maximum input level of +32.5 dB on 20 kOhm impedancy.
Now what would be the appropriate output level of the ADI-2 Pro FS?
Thank you very much for your help.
Best regards
I have been thinking about a solution and this is what came up:
I would try all different output settings from +24 dBu, +19 dBu, +13 dBu to +4 dBu at nearly 0 dB FS with a sine sweap. The output ADI-2 Pro FS goes to the input of the headphone amp. Then I'd like to connect the XLR output of the headphone amp back to ADI-2 Pro FS input, without amplifing. The measurements will give insight of THD+N and noise floor. Any ideas what the criteria for a clean signal is?
Is this a reliable idea to measure or shoud I get in touch with the vendor instead?
Best regards
May I ask the question back, for what purpose you need a phonitor 2 cascaded behind the ADI-2 Pro FS ?
You are aware of that you can use the remap key feature of the ADI2 Pro FS
- to select between Phones and Speakers (with a slow rampup of volume)
- to mute all
- and more
The Auto Reference Level function of the ADI-2 Pro takes already care
to get optimum D/A conversion quality at every output level.
Maybe the room simulation for phones might be different to the ADI-2 Pro FS,
but tbh, I prefer more the dynamic loudness feature rather than to use room simulation when using phones.
I personally do not like it when the original signal becomes modified to much by room simulatio, no matter how its designed.
And to answer your question, simply use Auto Reference level and then simply use an output volume that your phonitor is able to handle well. The ADI-2 Pro FS supports you by showing in the display which Reference Level is being used when you change the output volume.
BTW ... I wrote a blog article how to best integrate an ADI-2 Pro into a setup:
https://www.tonstudio-forum.de/blog/ind … tup-EN-DE/
Thats how do it behind an UFX+ recording interface to connect my studio monitors and Audeze LCD-3.
With the remap-key option I have a very nice control over my setup
- to switch between phones and monitors with a slow ramp-up of volume
- to mute all outputs
- etc ..
The only reason for the Phonitor might be room simulation. But then tbh I would be more worried
about the modification of the audio signal itself than which output level to choose (as this is being
done in an optimum way by the ADI-2 Pro itself if you configure Auto Ref Level).
Thank you very much for your answer! It helped me a lot to get a workaround for the output level.
I already own the Phonitor 2 and I believe it is a great amp so far. I am not really interested in room simulation stuff. What makes me more curious is the comparision between the two amplifiers: ADI-2 Pro FS vs Phonitor 2.
My goal is to drive a Sennheiser HD 820 or a STAX SR-009S on one of these two amps. So I want to be certain to get every detail squeezed out. That's why I want to compare both amps in terms of measurement and listening before I decide which one I use as "main amp".
The Phonitor and ADI-2 Pro are 2 very different animals.
The Phonitor doesn't perform any kind of D/A conversion. He gets a line signal in which is already analogue and brings this to phones level for different kinds of phones, dynamic, symmetric and electostatic.
The ADI-2 Pro FS is a DAC, A/D, D/A converter and performs reference quality D/A conversion and with advanced features which you find nowhere else. So in your signal flow you should stay as long as possible digital, to FINALLY perform D/A conversion on the ADI-2 Pro FS.
But after that it makes no real sense to add another phones pre-amp in the signal chain. You have already a reference grade phone preamp with the ADI-2 Pro FS and the D/A conversion already took place there.
Therefore its best is to connect Phones directly to the ADI-2 Pro FS !
To your questions:
a) Sennheiser HD 820: connect it directly to the ADI-2 Pro FS.
b) Stax Solution: best you buy the Stax with one of the Stax Preamps and connect the Stax Preamp on the symmetric Line Out of the ADI-2 Pro. There I would make no compromises and go for a complete combination of Stax Preamp and Stax Phones. The Stax Premp performs AFAIK no D/A conversion, so it makes sense to connect it to the Line Out of the ADI-2 Pro FS. By this you automatically participate from Dynamic Loudness, etc.
An alternative solution:
Go for very good electromagnetic phones like Audeze LCD-X or LCD-3 or LCD-4.
Even Rob Katz was amazed about the LCD-X's precise Bass and was exactly this missing then in his very expensive Stax solution. So .. when even a Stax is not perfect, then I would save the money to buy Stax Preamp / Phones combination and get very good elektromagnetic phones.
Many Years ago there was no alternative to Electrostatic Phones, but with the availability of very strong Neodym magnets and new ideas in this business, magnetostatic phones become an alternative to electrostatic phones.
The Audeze phones which Rob Katz tried against his Stax was the model LCD-X.
This is ideal for a mixing and mastering engineer.
For simple listening to Music I would rather than that go for a LCD-3. With alcantara leather (this leather resulted for me in a sweeter sound as the reflections are different to the black leather option.
There is an even more expensive version the LCD-4, but I have some doubts that its worth the price differency.
Newer models of Audeze phones are sold without the relatively pricy support bag and with a more comfortably headband of the LCD-4 model. Even though the phones are quite heavy they managed it to make them sitting comfortably on your head.
By the smooth headband and i.e. by the alcantara leather.
My experience with Sennheiser (HD800) is not so good, sorry:
- no bass
- the phones cubs were so large that my ears didn't find a good position
- phones were shaking on my head, no fix position when you move your head (nogo for me)
So in total a real disappointment against Audeze LCD-X, LCD-3.
I wrote a review in German, maybe it helps, hope that google translation is not too bad ...
https://www.tonstudio-forum.de/blog/ind … ADI-2-Pro/
Here the PDF: https://www.tonstudio-forum.de/index.ph … -v1-0-pdf/
I am personally very satisfied with the combination of ADI-2 Pro and Audeze LCD-3.
The magnetistatic phones bring to you a very good sound with defined natural sounding bass.
I personally have doubts that a Stax solution brings you so much more, because then the much more expensive Stax solution should be perfect. But if the Bass is not as perfect as with an LCD-X, well then I doubt that it makes sense to spend so much money on a Stax. TBH, I never heard a Stax, but its already enough for me to read from Bob Katz, that after listening the LCD-X, that he was not satisfied with his Stax anymore in the "Bass departement". I know the LCD-X and know how well and defined this bass is. Nearly the same like with the LCD-3 (which is a little bit more "HiFi").
Choose wisely !
You are right, for a STAX amplifier it makes no sense to use it between a Phonitor. I wasn't trying to do that anyway 
But why do you think it makes no sense to use the Phonitor after a D/A conversion from the ADI-2 DAC FS XLR out instead?
As I mentioned the scenario could be very true that measurments and sonic quality could differ from these two amplifiers. That's why I am willing to measure the amplifiers objectively in following environment:
D/A ADI-2 Pro FS (XLR out) → Phonitor 2 (XLR out) → ADI-2 Pro FS A/D
D/A ADI-2 Pro FS (Headphones Out) → ADI-2 Pro FS A/D
The results will be posted as soon as possible, estimated in August.
> But why do you think it makes no sense to use the Phonitor after a D/A conversion from the ADI-2 DAC FS XLR out instead?
Sure try it out if you want.
My personal opinion is that the ADI-2 Pro has already an extremely good phones section, therefore I would avoid to put more and more circuits in between D/A converter and phones.
The ADI-2 Pro easily drives HD800, 800S and the new 820 (tested last week) until your ears bleed and the driver's cones start crackling.
I would expect the specs to suffer if you put an external headamp in the loop, so let's hear what you find out.
I ordered my ADI-2 Pro FS today, and I am really looking forward to write down my insights about the upcoming measurments.
Just to get feeded I made a shootout:
UA2192 DA → SPL Phonitor 2 → AD UA2192
UA2192 DA → Drawmer MC 2.1 → AD UA2192
same cables, same Sinus at 1 kHz, -1 dBFS.
Without going into detail it turned out that the MC 2.1 has four times more THD against the Phonitor 2. These are relative shootouts with the UA2192, so I'd like to keep the results for myself until I can do them with the ADI-2 Pro FS.
Thank you to have been waited patiently for the promised measurements. I wanted to confirm the outmost best results for each device, so I woudln’t jump into hasty conclusions. Please let me explain how I made the measurements:
First measurement chain: ADI-2 DAC Pro FS D/A, Jack Output (Balanced Mode, High Power Output) → ADI-2 DAC Pro FS A/D, XLR Input +24dBu (at -4.5 dB)
Second measurement chain: ADI-2 DAC Pro FS D/A, XLR Output D/A → SPL Phonitor 2, XLR Input → SPL Phonitor 2, XLR Output → ADI-2 DAC Pro FS A/D, XLR Input +24dBu (at 0 dB)
I generated a sine wave in ARTA at 32 Bit 44.1 kHz at -1dBFS. I used the exact same copy of the generated sine wave to ensure the equality for both results. For the In- and the Output stage the sine wave should stay at an amplitude of -1dBFS, so one can observe the Total Harmonic Distortion+Noise (THD+N), given by the two systems. I experimented a lot with different In- and Output levels to ensure the lowest possibe noise floor level for each measurement.
The used Neutrik cables are different, (Jack - XLR, XLR - XLR) but they shouldn’t affect the results. Please also note that the A/D stage generates additional noise and harmonic distortion. As I said before, the measurements are relative – Please keep that in mind.
First measurement: THD 0.00019%, THD+N 0.00028%
Second measurement: THD 0.00032%, THD+N 0.00069%
Originally used sine wave, generated with ARTA, 44.1 kHz, 32 Bit.
To justify the thread: use low-power mode for the internal headphone amp whenever you can.
Use balanced if possible. Don't use the Hi-power mode if you have enough headroom, it generates additionally noisefloor.
I must confess: I was shocked when I first hit the play button to listen to my favorite music. I had the impression everything is to digital clean and somewhat sharp. But it's rather crystal clear like a deep lake, which I couldn't see before. Really mindblowing!
Having exchanged my previous Master Clock and switched to the internal headphone amp, the ADI-2 Pro FS, makes my life definitely feeling really really good while getting the tunes done.
Thank you RME.
Balanced is not required in cases like with the Audeze LCD-3 and others where the cables to the phones are directly split at the Plug.
There is no additional benefit of using balanced connection mode in such cases.
To justify the thread: use +24dBu for the internal headphone amp where you can.
Use balanced if possible. Don't use the hi-power mode if you have enough headroom, it generates additionally noisefloor
That statement makes no sense. There is no +24 dBu setting for the phones, only Low Power and High Power. The latter equals +22 dBu but you said one shoudn't use it...headscratch...
@ramses I am not sure if I got your point right. Don't you think it's worth getting a higher S/N ratio, as well as overall better audio signal? In my measurents I compared apples to apples, so I compared balanced out-and inputs. Is something wrong with my idea?
@MC right, I made a mistake. I exchanged the phone high-output level with the main output maximum level of +24 dBu. My statement should be corrected: As long as the following device after the main output supports a equal or highter input level than +24 dBu, one should use it.
What I wanted to say about the headphones output: as long as the phones output level is sufficient in loudness and stays equal or under 0 dBFS, one shouldn't use the hi-output level due to the lower S/N ratio.
@ramses I am not sure if I got your point right. Don't you think it's worth getting a higher S/N ratio, as well as overall better audio signal? In my measurents I compared apples to apples, so I compared balanced out-and inputs. Is something wrong with my idea?
SNR is already at such a low level between 118-120 dBA.. do you think you can hear the 3-4 dBA difference when using balanced ? There are HiFi High End Amplifiers out which deliver lower SNR. And if you should be even audiophile analog guy ... Do you think you get this SNR out of Vinyl or Tape ?
Therefore for me this doesn't justify to invest around 200-500 € in special balanced cables for only 3-4 dBA more SNR in that already high range of 118-120 dBA.
This money I would more use to invest into an additional LCD-X for mastering.
Phones 1/2
• Rauschabstand (SNR) @ +22 dBu: 117 dB RMS unbewertet, 120 dBA
• Rauschabstand (SNR) @ +7 dBu: 114 dB RMS unbewertet, 118 dBA
Balanced Phones mode
• Rauschabstand (SNR) @ +28 dBu: 120 dB RMS unbewertet, 123 dBA
• Rauschabstand (SNR) @ +13 dBu: 118.4 dB RMS unbewertet, 122 dBA
@MC right, I made a mistake. I exchanged the phone high-output level with the main output maximum level of +24 dBu. My statement should be corrected: As long as the following device after the main output supports a equal or highter input level than +24 dBu, one should use it.
Understand. Can you still edit your own post or should I add the info in there?
What I wanted to say about the headphones output: as long as the phones output level is sufficient in loudness and stays equal or under 0 dBFS, one shouldn't use the hi-output level due to the lower S/N ratio.
The S/N ratio is of less importance as usually you can't hear any noise either way. If you can then the choice is obvious. If not then hearing damage at too high volumes is a much bigger concern and reason to stay at Low Power (and the reason we ship the unit that way).
ramses wrote:
SNR is already at such a low level between 118-120 dBA.. do you think you can hear the 3-4 dBA difference when using balanced ?
I don't want to judge what a human is able to hear and what not. I say it's visually calculated that we can see obviously a difference. Apart from that, I think that a balanced headphone setup makes as much sense as connecting microphones together with balanced cables. Have you ever compared an unbalanced with a balanced cable with your microphones? You bet what's better.
MC wrote:
Can you still edit your own post or should I add the info in there?
All right, I edited my post.
Mic cables / balanced connections can become ~100+ meters long. For this main reason balanced connections and the higher studio levels exist.
Sorry, but for 3m phones cables which in 99% of all cases not even run in parallel with energy lines this is not required and nothing more than an extravagance.
Mic cables run extremely low level signals at higher impedances, one cannot compare this to a phones output situation. The ADI's 0.1 Ohms output impedance makes balanced cable as much needed as with loudspeakers - not at all.
@ Ramses:
> do you think you can hear the 3-4 dBA difference when using balanced ?
First the difference is 3 dB rms unweighted (around 6.5 dBA). Second the noise level is 3 dB higher! Means it's getting worse unless you need the extreme high level that balanced offers (+28 dBu), where you then have 3 dB more dynamic range compared to unbalanced. That is clearly explained in the manual. 'While the signal rises by 6 dB, noise rises by only 3 dB.'
RME User Forum → ADI-2 & 2/4 Pro series, ADI-2 DAC series → ADI-2 Pro FS to Headphone Amp, what is the optimal output setting?
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