Measurements of RME ADI-2 DAC and Headphone Amp

[ReaderZ]

With regard to this issue, whereby a faint buzz can be heard from the speakers when the power amp is switched on, but the RME DAC is in standby. Some have suggested that this might be a ground loop, or grounding issue. It occurs to me that the ADI DAC isn't grounded, it has no direct connection to earth - "floating ground"?

View attachment 60877

Presumably, the ADI DAC uses a virtual ground, generated by a circuit along these lines:

More info here: https://www.goldpt.com/virtual_ground_circuit.html

Therefore, ground doesn't exist unless the unit and the circuit are powered.

I'm taking some wild stabs in the dark here, my electronics knowledge is pretty limited, so, people that actually know what they're talking about, how did I do?

I have no idea, but good to know it doesn't have ground plug... guess nothing is perfect.

 

[Schackmannen]

Maybe @MC_RME can shed some light on the issue?

 

[th0m]

Does anyone have any suggestions regarding EQ settings when using HD650's?

I'm curious since I have a pair on order after not owning any fullsize cans for years and it will be interesting to see if my ADI-2 can make them even better than I remember.

 

[ShiZo]

Does anyone have any suggestions regarding EQ settings when using HD650's?

I'm curious since I have a pair on order after not owning any fullsize cans for years and it will be interesting to see if my ADI-2 can make them even better than I remember.

No eq on my adi 2 dac and the 650 sound amazing, only beaten by my focal clear.

 

[DJBonoBobo]

With regard to this issue, whereby a faint buzz can be heard from the speakers when the power amp is switched on, but the RME DAC is in standby. Some have suggested that this might be a ground loop, or grounding issue. It occurs to me that the ADI DAC isn't grounded, it has no direct connection to earth - "floating ground"?

View attachment 60877

Presumably, the ADI DAC uses a virtual ground, generated by a circuit along these lines:

More info here: https://www.goldpt.com/virtual_ground_circuit.html

Therefore, ground doesn't exist unless the unit and the circuit are powered.

I'm taking some wild stabs in the dark here, my electronics knowledge is pretty limited, so, people that actually know what they're talking about, how did I do?

I had the same "non-issue" (quiet buzzing when RME switched off, silent when switched on). Setup is PC -> USB -> ADI-2 -> XLR -> active monitors. Because of a suggestion by MC on the RME-forum (https://forum.rme-audio.de/viewtopic.php?pid=137638#p137638) i bought an Intona USB Isolator and the noise is gone.

 

[rickyhgarcia]

View attachment 60877

I have a PS Audio C7 power cord. Very nice power cord. I wonder if it can be used on the RME transformer because the picture shows "round" for both prongs. My cable is "square" on one side. Can the "square" be filed on the cable without harm? Or is it square for specific use of the cable?

 

[ShiZo]

Yes you can. I've done it with the pangea c7. Probably doesn't do anything. And someone here can prove it likely.

I have such a jumble of so many different kinds of cords behind my desk (ethernet, USB, ac power cords, coaxial, transformers for devices). So I paid attention to shielding.

 

[ReaderZ]

Yes you can. I've done it with the pangea c7. Probably doesn't do anything. And someone here can prove it likely.

I have such a jumble of so many different kinds of cords behind my desk (ethernet, USB, ac power cords, coaxial, transformers for devices). So I paid attention to shielding.

This reminds when someone asked manufacturer of very high end studio monitor the importance of power cord, the answer was something like 'it's very important, you have to make sure it's long enough to reach the power socket, else you get no power'

 

[soundwave76]

Does anyone have any suggestions regarding EQ settings when using HD650's?

I'm curious since I have a pair on order after not owning any fullsize cans for years and it will be interesting to see if my ADI-2 can make them even better than I remember.

Definetly try EQ! Check Rtings and Oratory Reddit thread for 650 measurements and then apply EQ accordingly. Practical tips can be found here on this forum if you search for a thread about Stax L300 Limited headphones.

 

[Count Arthur]

I have a PS Audio C7 power cord. Very nice power cord. I wonder if it can be used on the RME transformer because the picture shows "round" for both prongs. My cable is "square" on one side. Can the "square" be filed on the cable without harm? Or is it square for specific use of the cable?

I suspect that changing the mains cable to the power supply would do precisely nothing. I don't think the quality of the cable, or the power supply is an issue, it's the fact that the RME ADI-2 isn't connected to mains ground at all.

I'm not willing to do this to my DAC; I switch everything off when I'm not using it, so it's not really an issue for me. However, I suspect that if you connected pin 1, ground, of each of the XLR sockets to earth/ground it would solve the problem:

I had the same "non-issue" (quiet buzzing when RME switched off, silent when switched on). Setup is PC -> USB -> ADI-2 -> XLR -> active monitors. Because of a suggestion by MC on the RME-forum (https://forum.rme-audio.de/viewtopic.php?pid=137638#p137638) i bought an Intona USB Isolator and the noise is gone.

That's an expensive way to fix a problem that only occurs with an item when you're not using it.

 

[Kundroc]

I'm not willing to do this to my DAC; I switch everything off when I'm not using it, so it's not really an issue for me. However, I suspect that if you connected pin 1, ground, of each of the XLR sockets to earth/ground it would solve the problem:

Are you sure, this has not already been taken care of (pin 1 connected to case at connector)?

 

[Count Arthur]

Are you sure, this has not already been taken care of (pin 1 connected to case at connector)?

It may well be that the XLR sockets they've used have that feature for when they are used in a grounded chassis, but the RME chassis isn't connected to ground, because there is only a DC power connection with a +ve and -ve conductor and no connection to mains earth.

 

[ShiZo]

I've seen the designer say that it has a 10 Layer PCB and multiple ground connections.

 

[Count Arthur]

You can have a virtual ground in a purely DC, battery powered circuit, see my previous post, but that's not the same as a ground that's connected to mains earth.

Mains earth, will always be there, open up pretty much any electrical item and you'll see that only the live, or live and neutral are switched, the earth will not be and will always be connected to both the circuit and the chassis, if it's metal. Whereas as a virtual ground is a 0v reference point created between a +ve and -ve rails within a DC circuit and only exists when the circuit is powered: https://tangentsoft.net/elec/vgrounds.html

 

[HerbertWest]

It doesn't have its own sound signature. You just get the song but incredibly detailed.

To me things really only sound "right" or "colored" and I perceive a level of detail (not perfectly).

Hi ShiZo,

from your subjective experience, do you prefer the headphone out from the ADI-2, or from your HPA4 (they seem paired in your avatar pic)?
I am curious about if and how the HPA4 is improving the audio experience you get from the ADI-2; from what I'm reading here, the ADI can work as a competent stereo preamp, too.
I've read all the tests so far, but I do appreciate anecdotal experience on top of objective data

Thank you!

 

[ShiZo]

Hpa4, no idea why. The adi's amp was the first one that blew me away though, I went from a schiit jotunheim (that I hated) to a questyle cma400i (sounded underpowered, almost made me miss the jotunheim's higher noise floor but louder sound) to the rme adi 2 dac (which like i said, blew me away, detail and enough power for days).

But I definitely don't seem to be immune to subjective bias. Maybe it sounds better to me because I want it to or think it should? I even have a linear power supply for my rme adi 2 dac which is a no no around these parts, especially with such good power filtering on the rme dac. I do consider myself an objectivist though in the sense that measured performance is very important, but I feel like I hear differences in dac filters etc. I even had my friend help me blind test the filters, sd sharp vs sharp and I was able to pick them out almost every time. I think I was only able to do that because I studied how they sounded beforehand and would listen to those changes. Something about the sharp filter allowed more detail whereas the sd sharp seemed to have more bass impact but would kinda overpower other notes. I've had my hearing checked out and have really good hearing though, especially for someone my age. So that makes me wonder how good some people's hearing can truly be, but it's just a wonder, as I'm no scientist.

As far as subjective experience, I really noticed it's deference in the treble. Something about the hpa4's treble is so realistic it's almost unbelievable. So there wasn't much difference in my subjective experience, I chalked it up to the thx module lowering crosstalk, but I really have no idea, most likely just bias. I did want the xlr output too, maybe that can have something to do with it? I know technically that's not supposed to be true though. But you forced my hand for my subjective experience, so there you go , kinda feel dirty doing it here though, on an audioscience forum . I "felt" like I noticed a difference in the treble. Almost everything else the same though and if I was forced to try to blind test all I would focus on would be the treble because of that.

 

[HerbertWest]

Ahah I'll bear my share of guilt for asking about subjective user feedback Quoting Amazon's founder: "when data and anecdotes don't match, the latter tend to be right", mostly because we deal with complex systems, and have to keep iterating on better ways to measure them.
Really appreciate your datapoint - not sure how many in the forum have the same setup, but your avatar was very revealing so I thought about asking.

 

[guildenstern]

A question for owners of the RME ADI-2 DAC FS:

Do you leave the display on all the time, or do you use the "AutoDark" mode to turn the display off after about 10 seconds?

Thanks!

 

[maverickronin]

A question for owners of the RME ADI-2 DAC FS:

Do you leave the display on all the time, or do you use the "AutoDark" mode to turn the display off after about 10 seconds?

Thanks!

I have a shortcut button to toggle it on and off. I leave the autodark off during the day and usually turn it on in the evening.

 

[Schackmannen]

I leave it on because I like to watch the spectrum display sometimes