An analogy I often use is the one of audio quality being like a 100cm ruler (Meter stick), where 1cm is you or me on day one, week one, with a cassette 4-track and 100cm is Abbey Road or similar very high end studio. Most of us with a modern DAW and a modest budget these days can get towards about the 90cm mark but getting the last 10cm gets expensive. I have been trying to squeeze every last centimeter out of my recording and mixing chain, which led me to the RME ADI-2 Pro which amongst other things is a stunning sounding stereo analogue to digital converter. Perfect for the final A/D in my hybrid studio workflow to go from the stereo output of my analog console into my DAW. But let’s also take a look at what else this very powerful half-u rack unit can do.

Why Do You Need A Dedicated A/D Converter?

The short answer here is you don’t NEED one at all. If you are working in the box and don’t use external analogue hardware you really do not need to worry. I however, have chosen not to work this way. I like to use both in-the-box processing and outboard hardware, oh and did I mention I have an analogue console (somebody take a drink). So what I need is either a master, two channel stereo recorder (hardware) or to get the output from my console back into the DAW. Now I could use two channels of my audio interface but here is why I do not do this by choice.

If I’m looking to buy some new gear like an interface (like that ever happens) I look at what I call the £ per analogue channel figure. If an interface has 8 channels of analogue I/O and it costs £800 then that’s £100 per channel. Simple maths. In today’s world of cost effective mic preamp chips and A/D-D/A converters you can get units where the £ per channel is as low as £8, but I’m not sure I want to be using that for the final stage of my work of musical genius.

So what I have done is looked for a dedicated A/D converter with much higher specs and consequently a “higher” £ per channel amount (around about £500 per channel in my case). The theory being that a higher the £ per channel is, the better the quality of the audio path and A/D conversion, which should result in better sounding recordings, mixes or masters and there are a great many companies out there who make just such a box for pretty much all price points.

The RME ADI-2 Pro FS

The new ADI-2 Pro FS from RME is one of that amazing bread of problem solvers. It’s packs a lot of features and processing into a very small 1/2U rack space. Although I’m using it as a master A/D audio converter this is one of those units that ticks a lot of pro audio use boxes.

RME ADI-2 Pro FS Features

• High quality AD/DA Conversion

• Double Headphone Amplifier (TRS Jack)

• USB-2 Digital To Analogue Converter (DAC)

• High quality front end and headphone amp for iOS devices

• Front end AD/DA for measurements systems up to 768KHz sample rate

• SPDIF/ADAT playback system with sample rate conversion

• Direct Stream Digital (DSD) recording and playing solution

Analogue & Digital Connectivity

• 2 Ch. Analog In / 4 Ch. Analog Out

• XLR Combi Jack Balanced Inputs

• XLR (Balanced) and TS (Unbalanced) outputs

• ADAT or SPDIF I/O optical

• AES/EBU and SPDIF coaxial

• 2 Extreme Power Headphone Outputs

• USB 2.0

The front panel of the unit is where most of the action happens with the main very sexy power button, twin gold plated headphone jacks, master controls including the main volume encoder and very high resolution back lit LED screen.

Around the back with have our analogue, power, USB-2 and digital optical connections, while the AES/EBU and coax SPDIF are connected via the included breakout cable. Now I’m not a massive fan of breakout cables but in this case it saves on a great deal of back panel real estate and of course there are plenty of applications where you don’t need all the digital connections, so they can be detached. The External PSU is also connected around the back, while I’m also not a fan of external PSUs I totally understand in this case why RME have done it…. to save space and I’m sure heat as this little box does get quite toasty. As yet I have not racked it up but if and when I do, I’ll be leaving plenty of space around it for ventilation.

The ADI-2 Pro is all metal construction and built like a small, yet perfectly formed tank.

In Use

As I have said before the AD-2 Pro FS is a real pro audio problem solver. Now I can’t really talk about all the use cases because I bought (yes bought) this unit for one job, to be the final stage of A/D conversion back into my DAW. The connections were very simple. I took a stereo pair of balanced outputs from my Audient ASP8024HE console and fed these into the 2 XLR inputs on the back of the ADI-2 Pro. I then took a pair of digital XLR cables and fed the AES/EBU Out to the AES Input on my Apollo X16 and the AES/EBU out of the X16 to the AES Input on the ADI-2 Pro digital breakout. I’ve also been using the new Antelope Orion 32+ Gen3, which only has coaxial SPDIF, so I have also connected a pair of 75 ohm phono terminated digital cables to this unit. Now one of the very neat things the ADI-2 Pro does, is it works out what you want it to do from what you feed it, then it just gets on and does what it thinks you need and it does it very very well.

Navigation

Along with the main volume/command pot there are 2 smaller notched encoders (which also act as buttons) and 4 small black buttons marked Vol, I/O, EQ and Setup. As you might have guest these do exactly what they say on the tin, and get you into the different control modes of the ADI-2 Pro. Once you get the hang of navigating using a combination of the 4 buttons, 2 press pots and the main volume the ADI-2 Pro is simple to navigate and the screen, as you can see below is nice and bright and clear.

The EQ deserves a special mention. Now for my application I’m not using this on the main outputs, but I am able to employ the EQ only on the headphone outputs which is very handy if you are using the ADI-2 Pro as an extra headphone amp for the bass player recording live in the studio and you want to give them a little more BASS without adjusting the tone of the main mix or other headphone mixes. It’s these sort of problems that the ADI-2 Pro takes in its stride.

Clocking

In any digital audio system there must only be ONE clock master. A digital time keeper that all other digitally connected devices must sync and lock up to. There are several ways of doing this. One way, and the most common is to use digital Word-Clock connected over a 75 ohm BNC terminated cable. Sadly the ADI-2 Pro does not have a Word-Clock connection. Instead RME believe the clock signal should be part of the digital audio connection, either inside the Optical or Coax ADAT, AES/EBU or SPDIF digital stream. But the real question is which device should be the clock master? Again there are many theories and ideas about this but I have been told the A/D should also be the clock master, but if you own units like the UA Apollo X16 or Antelope Orion32+ you are giving up on what those companies say are some of the key features of their interfaces, fantastic digital clocking.

I have tried the ADI-2 Pro as both a digital slave and as digital master with the interfaces slaving to it and I have to say I really can’t hear a difference. I’m not saying there is not a difference, but I can’t hear it. For what it’s worth, I’m setting the ADI-2 to be the slave, as it can automatically adjust to the sample rate of the clock coming into it, and that makes it one less thing I have to remember when setting up a session. All my ducks, or should that be clocks are in alignment and I don’t have to think about it.

Conclusion

For a small unit the ADI-2 Pro FS really does pack a punch with a host of really useful features and benefits. So far I have only scratched the surface of what it can really do but for me it’s primary use is as my final A/D converter. This is does very well indeed. I believe the quality of my output is better for using the ADI-2 Pro over just using another pair of channels on my audio interface.

Having another 2 super loud and clean headphone outputs is also very very useful when tracking.

Currently you can pick up an RME ADI-2 Pro FS for around £1200 UK Pounds from online resellers, which is an absolute snip when compared to some of the seriously high end AD/DA or DAC converters, but if you can get to a dealer to check this baby out you really should. RME have really crammed a great deal into this half U rack unit and I’m sure even if you are not employing a hybrid workflow the ADI-2 Pro has something to offer your studio, post or live production facility.

Thanks to our friends at Synthax Audio UK for getting me the ADI-2 Pro to play with. You can find out more about the RME ADI-2 Pro FS on the Synthax UK website.