User Manual

User’s Guide ADI-2 Pro – v 1.91

Will this cause a deterioration in sound?

No, for two reasons. The input of the ADI-2 Pro has an impedance of 9 kOhm, which is high

enough to not overstrain even older Hi-Fi units with higher impedance outputs (up to 1 kOhm).

That is even more true with newer units having outputs significantly below 1 kOhm. Additionally

the input of the ADI-2 Pro has been designed to have the exact same technical specifications,

no matter if a balanced (XLR) or unbalanced (mono 6.35 mm) signal is applied. RME's servo-

balanced input also provides an automatic level correction - so that even the reference levels

are identical.

With the outputs such an adapter causes no change at all - technical specifications and opera-

tion stay unchanged. The outputs of the ADI-2 Pro serve RCA inputs without any problem.

Do the advantages of the ADI-2 Pro's fully symmetrical design still exist when using un-

balanced connections (RCA)?

Yes. Because the unbalanced input signal is internally converted to balanced directly after the

first input stage. On the output side RME uses a specially developed servo-balanced DAC filter,

which provides both paths of the balanced design to have full noise and distortion ratios. There-

fore the technical specifications are reached even if the balanced XLR output is used unbal-

anced, disconnecting one pin - the required signal optimization is already done in the unit. At

the typical RCA output, the TS socket with plugged in adapter, an additional conversion bal-

anced to unbalanced is performed directly at the output. These efforts guarantee the supreme

sound quality of the ADI-2 Pro to be available in all operation and connection scenarios.

Which level setting is recommended?

As professional device the ADI-2 Pro offers input and output levels up to +24 dBu (12.24 V

RMS), which overwhelm standard Hi-Fi equipment. But that's no problem as a total of four ref-

erence levels are available. With Hi-Fi the setting +4 dBu (equals +1.78 dBV or 1.23 V RMS) is

recommended. This setting causes an ADI-2 Pro output level similar to that of many CD-

players. In case it is still too low simply change to +13 dBu (+10.8 dBV, 3.46 V RMS).

If the input level is still too low at a setting of +4 dBu, because the feeding unit's output level is

insufficient, I/O - Analog Input - Trim Gain will help to achieve up to 6 dB more level.

Doesn't such a low level cause a significant increase in noise?

Usually yes - but not with the ADI-2 Pro. Switching the reference levels is done in the analog

domain, in hardware. The circuit has been optimized for near maximum signal to noise ratio

even at +4 dBu. Detailed values can be found in chapter 33.1 / 33.2. The input's signal to noise

ratio can even be verified by anyone, using the free tool DIGICheck, function Bit Statistics &

Noise (see chapter 26 / 28). Please note that for measuring the signal to noise ratio or dynamic

the inputs need to be shorted (0 Ohm).

The loss of only about 1 dB of noise ratio at +4 dBu is an outstanding achievement of engineer-

ing. However, in real world situations DIGICheck will offer a lot more revealing information. As

soon as something is connected to the inputs of the ADI-2 Pro one has to say goodbye to those

dream values. The basic noise and hum, especially from Hi-Fi units, is magnitudes higher …