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RME ADI-2 FS Version 2 DAC and Headphone Amp Review

amirm

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#1
This is a review and detailed measurements of the updated version 2 of the RME ADI-2 FS DAC and headphone amplifier. It was kindly sent to me by the company. The cost us US $1,149.

The ADI-2 looks very nice in black with a bright, super responsive display (doesn't come out as well in the picture):

RME ADI-2 DAC FS Version 2 USB Headphone Amplifier Review.jpg


I usually only focus on performance of audio products and DACs don't have much to talk about anyway. Not so with RME products. There are tons and tons of features including two different headphone outputs with automatic detection and settings. There is a built-in parametric EQ which can help you optimize your room or headphones. And on and on.

The display is highly informative which I appreciate. I like to know what my settings are, sample rate, volume, etc. at a glance and they are all here and then some.

Soft white LEDs surround the power button, the main rotary controller and backlight for the switches.

A nice reassuring set of relays click on power on. A compact 12 volt, 2 amp power supply with a clever locking mechanism comes with the unit. As does a remote control (which I did not use).

The back panel is tidy:

RME ADI-2 DAC FS Version 2 USB Headphone Amplifier Back Panel Connectors Inputs Outputs Review.jpg


Of course the product is made in Germany which makes availability much better for our EU members. Support is superb on our forum and RME's own and company makes frequent updates to the unit through firmware updates.

Overall, this is a beautiful DAC with extensive feature list.

DAC Audio Measurements
Let's start with our usual dashboard of 1 kHz tone and measure what comes out of the XLR balanced connectors (used for all the DAC tests):

RME ADI-2 DAC FS Version 2 USB Audio Measurements.png


The distortion level now is state of the art with levels at -130 dB (15 dB better that best case human hearing). Noise level is higher though and dominates, resulting in SINAD of 115 dB. This is 3 dB better than version one of this DAC so definitely improved but not the best we have seen:

Best Pro Audio DAC.png


Yellow is the version 2 under test, and purple is the older one.

The reason noise level is not as good as seemingly cheaper DACs is because the ADI-2 is a pro product and can produce much higher output level. When we let it loose this way, performance improves yet again:

RME ADI-2 DAC FS Version 2 USB SINAD vs Level Audio Measurements.png


SINAD reaches a maximum of 117 dB now with nearly 7 volts output. You can use this higher level output with amplifiers like Benchmark, Purifi, hypex ncore, etc. to get the best performance out of them.

We can see that in our dynamic range tests:
RME ADI-2 DAC FS Version 2 USB Dynamic Range Audio Measurements.png


IMD test is likewise impacted by the output level although it is excellent both ways:
RME ADI-2 DAC FS Version 2 USB IMD Audio Measurements.png


There is tiniest hint of jitter (hugging our main tone of 12 kHz and a pair at 6.2 and 17.8 kHz) but at -140 dB and lower, are utterly inaudible:
RME ADI-2 DAC FS Version 2 USB Jitter Audio Measurements.png


32-tone test resembling "music" shows very low levels of intermodulation distortion:
RME ADI-2 DAC FS Version 2 USB Multitone Distortion Audio Measurements.png


Linearity is essentially perfect to the maximum level I measure:
RME ADI-2 DAC FS Version 2 USB Linearity Audio Measurements.png


There are a set of filters. In the interest of time, I just tested the default:

RME ADI-2 DAC FS Version 2 USB Filter Audio Measurements.png


THD+N versus frequency is low but perhaps not as perfect as it could be:

RME ADI-2 DAC FS Version 2 USB THD+N vs Frequency Audio Measurements.png


Headphone Amplifier Measurements
Since there is no analog input, these measurements are the combination of the performance of the DAC plus the headphone amplifier. With stand-alone analog headphone amplifiers, you would lose a few dBs of performance when you pair a DAC with them. Also, the volume control here is digital which means channel matching is excellent unlike analog solutions.

Let's start with our usual power measurement into 300 ohm:

RME ADI-2 DAC FS Version 2  Headphone Quarter inch Power into 300 ohm impedance Audio Measurem...png


310 milliwatts of power into 300 ohm is superb as my threshold of excellence is 100 milliwatts. This means you can drive high impedance headphones with ease. Combined DAC+amp in high power clocks at 110 dB SINAD which is just shy of best case theoretical threshold of hearing (again, 115 dB).

If you want lower noise, you can use the IEM output in low power mode (blue):

RME ADI-2 DAC FS Version 2  Headphone IEM Power into 300 ohm impedance Audio Measurements.png


You have three nice settings for three different scenarios.

Switching to 33 ohm load we get:
RME ADI-2 DAC FS Version 2  Headphone  Power into 33 ohm impedance Audio Measurements.png


We have 1.5 watts of power which should be good for most headphones. I did not bother to test the IEM output as the low power mode (red) already had excellent low noise performance.

I was surprised that with 50 millivolts output, performance was not as good as version 1:
Most quiet headphone amplifier review 2020.png


I use different fixtures to wire up to my analyzer so perhaps that is the reason for slight regression. Still, what is there at 89 dB, beats majority of headphone amplifiers out there.

I did not bother to measure the output impedance and trust the RME spec of it being near zero.

Headphone Listening Tests
I started testing with my Sennheiser HD-650. Wow, these sounded super with incredible amount of power available on tap. I had no trouble getting my ear lobes to resonate with bass heavy music! :D If I did not fear for quick loss of hearing, I would listen that way for hours. :) Ample power, low noise and distortion meant great dynamic range, detail, lack of noise, etc. Everything reflected the fidelity of the source.

I then switched to my super inefficient and low impedance (25 ohm) Ether CX headphone. Here performance was very good but I could get the amp to distort. Granted, by then it was too loud for me to tolerate but still, I like to see some headroom there. Again, these are super difficult headphones to drive.

Conclusions
The RME ADI-2 FS V2 improves on the first generation design in lowering distortion levels. The slick look and huge feature list is a major add-on which doesn't exist in DAC-only products. Headphone amplifier is very powerful and is able to drive most headphones with authority and high fidelity. No records have been broken on the performance though.

Overall combination of features and performance pushes me to give the RME ADI-2 FS DAC V2 my strong recommendation. Indeed, I am still listening to it as I type this and will make it my everyday DAC+amp at my workstation.

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As always, questions, comments, recommendations, etc. are welcome.

I have packed so many heavy and big boxes and dropped off at UPS store that I am starting to feel sorry for the guy there and want to buy him a gift. So please donate a few dollars toward that if you can. Be on notice though that I might be tempted to keep said money and just use it for myself. :) Here is the link: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
 

kn0ppers

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#4
RME doesn't disappoint. I am actually considering buying the updated ADI 2-Pro, very nice piece of kit as well. Just seems like a very well-rounded product series. I hope that impression doesn't change when I eventually buy one ;)
 

rajapruk

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#9
@pos this one should be able do drive the JBL M2 compression driver pretty good from the headphone output, or what do you think?

@amirm Any pop or cracks on startup/shutdown/sample rate change on this one? I guess not.
 
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Maxicut

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#11
I own the latest Pro version of this DAC with ADC and DIY XONO phono stage coupled with 2 Hypex NCore400 monoblocks into Martin Logan electrostats. It’s pure sonic bliss. I cannot imagine ever owning another DAC/preamp.
Might be a noob question, but why not just use the balanced outs of the RME to some powered monitors?
 

jae

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#12
Great as expected. The only thing disappointing to me about this the lack of internal power supply, and no headphone balanced out, although I wouldn't expect to see that in an RME product, however minor. Given the market I would also have thought it could at least have AES in.

The advantage of the chifi stuff like Topping D90/A90 stack etc., seems to be a more robust enclosure, more inputs, wireless, MQA, and a bit more power but at $100-200 more. I'm excited to see how the upgrade of a DX7 Pro (DX9 Pro? - based on D90/A90) will compete with this, as an all-in-one solution. There is a bit of a void in the market when it comes to high performing amp/dac combos.
 

VintageFlanker

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#14
Indeed, I am still listening to it as I type this and will make it my everyday DAC+amp at my workstation.
Yup. Where it belongs!;)

Not surprised one bit by the results. @MC_RME just made an already stellar DAC even better. That confirms the measurements published earlier on the ADI-2 DAC thread: Not only it performs great, but it exceeds the specs of the chip itself! (113dB THD+N).

I own this new version (ak 4493) and use it as a preamp, with iceedge as1200 amp. It's the heart of my system. Excellent combo
I use the exact same combo (with Apollon AS1200). Best preamp I've ever had.:cool:

Might be a noob question, but why not just use the balanced outs of the RME to some powered monitors?
Maybe because he needs to buy these powered monitors first? ;)
 
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kn0ppers

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#17
Yeah but what do you really need it for? If you don't need the extra voltage swing and the headphone amp section is properly implemented, there is little benefit of going balanced, you can achieve great performance in basically all metrics without it, as many amps tested here show. Headphones are "differential" by nature, their CMRR is infinite. Obviously having a shared ground connection conductor is supoptimal because it will have some impedance and thus create crosstalk, but if the headphone has ground conductors for each channel, this problem also practically doesn't exist.
 

jae

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#18
The RME ADI-2 Pro fs has Phone balanced out
That is true, but unfortunately it is not 4-pin XLR, I would rather just use SE in that case since the whole idea was to be able to use my existing 4-pin cables as-is without an adapter. It is not really a 'necessary' thing and really doesn't provide much benefit in a properly designed amplifier, but presumably this product was made for the audiophile market (as opposed to the PRO which is the professional market?), so I don't see why they wouldn't include a commonly desired feature/termination found in high-end audiophile products when virtually all similar products over $300 do. I would theorise that perhaps most people buying this would be using it with active monitors, but they bothered to include one of the best headamps on the market in this product, even with a separate IEM out, so it is obvious they are attempting to satisfy the high-end head/earphone niche as well.

I also heard the PRO specs a bit worse than the DAC as far as the dac performance goes, but I don't know if that has been addressed by a new revision. If the PRO's analogue inputs supported microphone preamps I would concede any shortcomings and use that product for everything, but alas it does not. I'm always trying to omit additional components whenever I can.
 
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amirm

amirm

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Thread Starter #19
@amirm Any pop or cracks on startup/shutdown/sample rate change on this one? I guess not.
I listened to it while putting my computer to sleep and it was quiet. There are a couple of relay clicks when you turn it on. I have to check to see if they come on when switching sample rates and such.
 
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amirm

amirm

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