Comparison RME ADI-2 Pro DAC vs RME ADI-2 DAC

Model of the digital-to-analogue converter installed in the device.

DAC in this case means the “heart” of the device, the main circuit that directly provides the conversion of digital audio to analogue. The name of the DAC model is given mainly for advertising purposes — as an illustration of the fact that high-quality components are used in the device. In addition, knowing the model, you can find detailed information about a particular DAC; although in fact such a need does not arise often, it may still arise in some specific cases.

The signal-to-noise ratio provided by the converter.

This parameter describes the ratio of the volume of the pure sound produced by the device to the volume of its own noise (which is inevitably created by any electronic device). Thus, the higher the signal-to-noise ratio, the clearer the sound, the less the DAC's own noise affects the audio signal. Indicators up to 80 dB can be considered acceptable, up to 100 dB — not bad, 100 – 120 dB — good, more than 120 dB — excellent. However, it is worth remembering that the overall sound quality is affected not only by this parameter, but also by many others.

Note that the signal-to-noise ratio is often associated with such a characteristic as the dynamic range (see above). They are similar in general meaning, both describe the difference between an extraneous background and a useful signal. However, the noise level in the calculations is taken differently: for the signal-to-noise ratio, the background of the converter “at idle” is taken into account, and for the dynamic range, the noise that occurs when a low-level signal is output. This is the reason for the difference in numbers.

The capacity of the analogue-to-digital converter installed in the device.

The principle of converting analogue audio to digital is that the sinusoid of the audio signal is divided into separate "steps", and the data about each "step" is encoded in digital form. This encoding has two parameters: sampling rate and bit depth. For the first, see the relevant paragraph; and it depends on the bit depth how accurately the height of each “step” will correspond to the height of the point of the sinusoid on which it falls. In fact, the higher the bit depth of the ADC, the higher the quality of its work, the more accurately the device converts analogue sound into digital.

The minimum indicator for ADCs used in modern audio interfaces is 16 bits — this corresponds to the bit depth of audio in the Audio CD format and is considered quite sufficient even for high-quality sound. However, there are also more advanced converters — 24 and even 32 bit.

The signal-to-noise ratio provided by the analogue-to-digital converter installed in the device.

This parameter describes the relationship between the level of the line level audio signal input to the transducer and the level of the device's inherent noise (which cannot be avoided in any electronic circuit). The higher this ratio, the “cleaner” the converter works, the less its own noise it introduces into the encoded digital signal. Indicators up to 80 dB can be considered acceptable, up to 100 dB — not bad, 100 – 120 dB — good, more than 120 dB — excellent.

Inputs provided in the design of the device.

— Mini-Jack (3.5 mm). A standard 3.5mm mini-jack is typically used as an analogue (line) audio input to two stereo channels. It is designed mainly for portable devices like smartphones, pocket players, etc.

— Jack (6.35 mm). Connector used as an analogue audio input. It is similar in design to the mini-Jack 3.5 mm (see the relevant paragraph), but it is larger and provides more reliable contact. As a result, this connector is not used for portable, but mainly for stationary audio equipment, including professional. The second feature is that the 6.35 mm Jack can play the role of both a line input and an instrument/mic input. The latter is found in audio interfaces (see "Type"), while such devices may be provided with combined connectors that combine Jack and XLR (see the relevant paragraph). In addition, it is worth noting that a balanced connection is often made through a 6.35 mm jack — a special kind of connection used in professional audio equipment and allowing you to transmit a signal without interference even over fairly long wires.

— RCA. Characteristic round connectors for a tulip-type plug; can be used in different interfaces, but "RCA input" usually means an analogue audio line input. Note that only one channel of audio can be transmitted through one analogue RCA connector; therefore,...the number of such connectors corresponds to the number of channels supported by the device (for example, a stereo input consists of a pair of RCA jacks).

— Phono. A specialized input for connecting a vinyl player, or rather, a turntable pickup. The peculiarity of the audio signal from the pickup is that it is “skewed” in frequencies, and in order to bring the frequency response back to normal, it is necessary to pass the sound through a phono stage. Accordingly, the presence of the Phono input means the presence of a phono stage in the device and the ability to work as a preamplifier for vinyl players. Keep in mind that there are two types of pickups — MM and MC, and before buying a device with a Phono input, it is advisable to check which of these varieties it is compatible with. However, it is not uncommon to find support for both options at once.

— XLR. In audio technology, three-pin XLR connectors are most often used. Theoretically, they can have different purposes, but in fact, when they say "XLR input", they usually mean an analogue audio input — either linear or microphone / instrumental (in the latter case, this connector can be combined with a 6.35 mm Jack — see the relevant paragraph). This connector is popular in professional audio equipment, and there are two main reasons for that. Firstly, XLR provides a reliable and tight connection; locks are often provided in the sockets to secure the plugs. Secondly, the connection through this connector is carried out by the so-called. in a balanced way, on three wires instead of two. The peculiarity of such signal transmission is that external interference is filtered, in fact, by the wire itself, which allows you to transmit a high-quality audio signal even with long cable lengths.

— Coaxial S / P-DIF. Input for a digital audio signal, one of the varieties of S / P-DIF (the second variety is optical). Allows you to transmit both stereo and multi-channel audio. RCA is used as a connector, but this input should not be confused with RCA inputs (see the relevant paragraph). The coaxial interface uses a fundamentally different signal format, all sound channels are transmitted through one connector, and even a special cable must be used for such a transmission — shielded. Compared to the fibre used in the optical interface, this cable is more susceptible to electromagnetic interference, but less delicate.

— Optical. Input for digital audio signal transmitted via TOSLINK fibre optic cable. This interface is a kind of S/P-DIF and is similar in capabilities to the coaxial input (see the relevant paragraph) — in particular, it allows you to transmit multi-channel audio. The key difference and the main advantage of such a connection is complete insensitivity to electromagnetic interference. On the other hand, fibre optic cable is quite fragile and susceptible to damage, it must be protected from strong pressure and bending.

— Balanced digital (AES / EBU). Professional interface for working with digital audio signal. Most often based on an XLR plug, but do not confuse the AES / EBU input with the XLR input: the first version works with a digital signal, where all audio channels are transmitted through a single connector, the second with an analogue one, according to the “one connector per channel” principle. But a common feature of both interfaces, in addition to the type of plug, is that they provide a balanced connection — a connection in a special format in which interference induced on the wire is extinguished directly in the wire. This allows long cable lengths to be used without compromising signal quality.

— MIDI. Input for connecting MIDI devices: keyboards, turntables and other controllers. These inputs are found exclusively in audio interfaces (see "Type"). Recall that a MIDI stream is not a sound, but service information for virtual musical instruments. Therefore, data received through this input is not processed by the device, but simply transferred to a computer, tablet or specialized equipment via USB type B (see below), MIDI output (see "Outputs") or another similar connector.

— BNC. Coaxial connector with bayonet or threaded fixation. Most often used similarly to coaxial S / P-DIF — to receive a digital audio signal. It is mainly used in professional equipment, one of the advantages is the presence of a latch, which increases the reliability of the connection.

— USB (type B). Connector for connecting to a computer as a peripheral device. It has a characteristic square shape, which is noticeably different from the well-known rectangular USB ports. And the methods of using such a connection can be different. So, traditional DACs (see "Type") when connected via USB Type B usually play the role of an external sound card and are used to output sound from a computer to headphones, speakers or other audio device. Audio interfaces, on the contrary, transmit the signal received from external sources to a computer for recording and processing.

— USB-C. The presence of a modern USB-C port for connecting to a PC or laptop. Like the USB port (type B), it can transmit a signal in two directions, depending on the type of device.

— IR control input. Connector for connecting a remote infrared receiver for the remote control. The role of such a receiver can be played either by a separate specialized device or by another component of the audio system that has an IR control output and is compatible with this remote control. The meaning of this function is that the DAC, after mounting all the components of the audio system, may end up in a place where the remote control “does not reach”. In this case, you can connect an external receiver to the device and send signals from the remote control to it, and the receiver will already transmit a signal to the controlled device.

— Trigger. Service input used to control the power of the device. This input is connected to the trigger output of another audio system component (such as an amplifier), and when this component is turned on / off, the DAC will turn on and off at the same time. This makes life easier for the user, eliminating the need for "excessive movements" to turn the DAC on and off.

— Mini-Jack (3.5 mm). In this case, we mean a standard 3.5 mm mini-Jack jack used as a line output (headphone outputs that also use this connector are counted separately — see the relevant paragraph). In fact, such a connector is mainly used to connect some models of active speakers (it is especially popular in computer acoustics). In this case, two stereo channels are usually output through one mini-Jack connector at once.

— Jack (6.35 mm). Analogue audio output. Being similar to the popular mini-Jack in design (and differing only in larger sizes), this connector has a fundamentally different application specifics. Firstly, Jack (TRS) plugs are used mainly in "serious" stationary audio equipment, including professional. Secondly, outputs of this type usually operate on a "one channel per plug" basis (i.e., for example, a stereo output consists of two jacks). Thirdly, this connector often provides a balanced connection — a connection in a special format that allows you to use long wires without compromising signal quality (due to the fact that the wire itself works as a noise filter). However, a 6.35 Jack connection can be unbalanced.

— RCA. In this case, we are talking about an analogue linear audio output using RCA connectors (these connectors can also be used in other interfaces, but they have their own names). The standard output of this type co...nsists of two connectors — for the left and right stereo channels. This interface is one of the most popular in entry-level and mid-level stationary audio equipment.

— XLR. Formally, XLR is the name of the plug type; however, when talking about XLR outputs, they usually mean a specific interface — an analogue line output with a balanced connection. Such a connection (with different connectors) is widely used in professional technology; it allows the use of long cable lengths without compromising signal quality, due to the fact that external interference is damped directly in the cable. Specifically, the XLR connector is notable for its high reliability, often in such connectors locks are provided for fixing the plugs. The signal to these outputs is fed on the principle of "one channel per connector", so the standard XLR output consists of two connectors — for the left and right stereo channels.

— Coaxial S / P-DIF. Digital audio output, capable of transmitting multi-channel audio. It uses an RCA type connector, but the S/P-DIF outputs are fundamentally different from the RCA outputs (see the relevant paragraph) — firstly, by the type of signal (digital, not analogue), and secondly, by the number of connectors (in S / P- DIF one connector is responsible for all sound channels). In addition, a regular RCA cable for a coaxial interface is not suitable — you need to use a shielded wire.

— Optical. Output for digital audio transmission (including multi-channel) via fibre optic cable. Such a connection is notable for its complete insensitivity to electrical interference, this is its main advantage over the coaxial S / P-DIF interface, which has similar capabilities. At the same time, optical fibre requires careful handling; a sharp bend or strong pressure can make such a cable unusable.

— Balanced digital (AES / EBU). Digital audio output via XLR connector. This connector differs from the XLR outputs (see the relevant paragraph), firstly, by the signal format, and secondly, by the fact that in this case all sound channels are transmitted through one connector. AES/EBU uses a balanced connection; such a connection makes it possible to use even fairly long wires without compromising sound quality, since interference induced on the cable is automatically filtered when receiving a signal.

— MIDI. Dedicated output for transmitting MIDI commands. It is found exclusively in audio interfaces (see "Type") that have a MIDI input (see above), and is used to transmit MIDI commands received by this input to an external device — most often a hardware sequencer or other specialized equipment.

— BNC. Coaxial connector, used primarily for digital audio transmission. It differs from the coaxial S / P-DIF (see above) not only in size, but also in the presence of a lock — bayonet or threaded — providing additional reliability of the connection.

— Trigger. Service connector used to control the power of audio system components connected to the device. When the DAC is turned on, the trigger output sends a control signal to the corresponding input of the controlled device (for example, an amplifier), “waking up” it; shutdown works the same way. Thus, the user does not need to enable and disable each component of the system separately — it is enough to enable / disable only the DAC, the controlled components will “respond” automatically.

The total number of headphone outputs provided in the DAC design.

Most models are designed for individual use, but there are exceptions - you can find models with 2 or more outputs on sale. The general idea of such a design is obvious: it allows you to connect several headphones at once and use the DAC for several listeners at once.

However, not all connectors can be of the same type. Among them are the classic mini-Jack (3.5 mm) and Jack (6.35 mm), as well as the less popular XLR and 4.4 mm Pentaconn.

— mini-Jack (3.5 mm). The most popular plug format among modern wired headphones. It is found in models of all price categories; and even high-end solutions that allow use with a more advanced 6.35 mm Jack most often have not a built-in Jack format connector, but a 3.5 mm plug and a complete adapter to 6.35 mm. On the other hand, in terms of acoustic properties, the mini-Jack is somewhat inferior to its "big brother".

— 6.35 mm (Jack). The plug format is designed mainly for fairly advanced equipment, mainly stationary. The large size of the connector makes it somewhat difficult to use in compact devices; on the other hand, due to this feature, the quality of the connection, reliability and noise immunity are significantly higher than with a more miniature 3.5 mm mini-Jack. And you can connect headphon...es with a mini-Jack plug to a Jack-type socket using a simple adapter; often such an adapter is even supplied with the "ears".

— XLR. This is a connector for mainly professional use, with a characteristic round shape, pin-shaped contacts, and often a lock on the rim for additional reliability in connection. This connector is used for the so-called balanced connection of headphones, which has a positive effect on the purity of the sound and allows you to use even long wires without additional risk of distortion. On the other hand, in the case of headphones, the need for such a connection arises relatively rarely, and there are not many “ears” with an XLR plug - these are mainly high-end professional models. So in amplifiers, outputs of this type are mainly used in premium-level stationary devices. Most often, a four-pin connector is used as such an output, often without a lock and / or of reduced size. In general, this type of connector is less common in audio equipment than the three-pin type, but it is the standard option in headphones, especially since 4 pins allow both stereo channels to be output through one jack (while three-pin jacks operate in the “one channel per jack” format). However, there are models where the role of a balanced headphone output is played by a pair of three-pin XLRs. At the same time, such connectors can be physically combined with 6.35 mm Jack outputs — in other words, the 6.35 mm jack is built right into the center of the XLR connector. This makes the design more compact, but does not allow both types of connectors to be used simultaneously.

— Pentaconn 4.4. A connection implemented by a 5-pin connector with a diameter of 4.4 mm. This is a relatively new balanced connection standard developed by Sony. Most often used as a linear output for digital-to-analog converters and amplifiers. Additionally, this connector can be found in multimedia players and even console consoles. The main advantage of the Pentaconn 4.4 standard is the ability to output an audio signal to fairly powerful high-impedance headphones. This standard is an alternative to the not very practical Jack and XLR connections.