Comparison S.M.S.L SD-192 Pro vs S.M.S.L M7

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.

Sample rate of the digital-to-analogue converter used 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. And the sampling rate is initially one of the characteristics of digital sound. In this case, its meaning is as follows: the sampling rate of the DAC must not be lower than the corresponding indicator in the incoming audio signal, otherwise the device will not be able to effectively cope with the conversion.

The bit depth of the digital-to-analogue converter used 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. Bit depth is initially one of the characteristics of a digital audio signal. In this case, its meaning is as follows: the bit depth of the DAC must be no lower than the bit depth of the audio signal with which the converter is planned to be used, otherwise the device will not be able to effectively cope with the conversion.

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 dynamic range of a transducer is defined as the ratio between the maximum signal level it is capable of delivering and the level of its own noise when a low amplitude signal is applied. Quite simply, this parameter can be described as the difference between the quietest and loudest sound that the device can produce.

The wider the dynamic range, the more advanced the DAC is considered, the better sound it can produce, all other things being equal. The minimum value for modern devices is about 90 dB, in top models this figure can reach 140 dB.

Also note that this parameter is similar in its meaning to the signal-to-noise ratio, however, these characteristics are measured in different ways; see below for more on this.

The coefficient of harmonic distortion produced by the converter during operation.

The lower this indicator, the clearer the sound produced by the device is, the less distortion is introduced into the audio signal. It is impossible to completely avoid such distortions, but it is possible to reduce them to a level that is not perceived by a person. It is believed that the human ear does not hear harmonics, the level of which is 0.5% and below. However, in high-end audio applications, distortion rates can be much lower — 0.005%, 0.001% or even less. This makes quite a practical sense: the distortions from the individual components of the system are summed up, and the lower the harmonic coefficient of each component, the less distortion there will be in the audible sound as a result.

Adjustments provided directly in the device.

— Bass adjustment. Separate bass level control; usually combined with treble control (see below). This function allows you to change the sound image by adjusting the volume of the bass sound relative to the rest of the frequency range.

— Treble adjustment. Separate treble control. Like the bass adjustment described above, it allows you to adjust the sound picture — in this case, by changing the volume of high frequencies relative to the rest of the range.

— Balance adjustment. Adjusts the sound balance between two stereo channels by increasing the volume for one channel and decreasing the volume for the other. Due to this, in the perception of the listener, the sound "shifts" towards greater volume. This function is mainly used for correction purposes — for example, if the speakers are at different distances from the listener, shifting the balance towards the far speaker allows you to compensate for the difference in audible volume.

— Level adjustment. Adjusting the overall signal level at the output, in other words, adjusting the volume. Adjusting the volume using the DAC's own control is sometimes more convenient than accessing the settings of other components of the audio system.

— Headphone level adjustment.... Headphone sound volume adjustment. This control is provided mainly for user comfort, it allows you to set the sound level in the "ears" to your own preferences. This possibility is especially relevant in light of the fact that headphones are rarely equipped with their own volume controls (and usually these are inexpensive models with relatively low sound quality).

— Sensitivity adjustment. Adjustment of input sensitivity of the converter. This function is found mainly in models with analogue inputs: it allows you to amplify the incoming signal, if necessary, even before it is processed by the converter, if the initial signal level is too low.

— ASIO support. Support for the ASIO audio standard. This feature is relevant when connected to a computer, when the device actually plays the role of an external sound card. ASIO technology is responsible for the interaction between specialized software and audio hardware; at the same time, it provides data transmission with minimal delay, which allows musicians and sound engineers to process sound in real time. This standard is used exclusively in operating systems of the Windows family, interaction with other operating systems is built in other ways (see in particular "MAC support").

— DSD support. The device supports the DSD standard, a specific digital audio signal standard that uses the so-called. pulse density modulation. The bit depth of such a signal is only 1 bit, but the sampling rate reaches 2822.4 kHz (64 times more than in the Audio CD format). Compared to the more common PCM standards, this format provides higher sound quality, better noise and error immunity, and lower noise levels. In general, DSD is considered a professional standard, and its support is found mainly in high-end equipment.

— MQA support. The device supports the MQA (Master Quality Authenticated) standard, designed to preserve and transmit the original quality of sound recordings in high resolution. The technology was invented by the...American company Meridian Audio. In fact, MQA improves standard digital audio by minimizing phase problems and pre-ringing/echo modulation effects. The technology uses special compression algorithms that allow high-quality audio files to be packaged into more compact sizes.

— I2S. Device support I2S standard. This is a digital audio format originally developed for "internal use" — for transmitting a signal between individual modules inside audio devices. However, more recently it has also been used for communication between individual components of audio systems. Note that this format does not have its own connector; various types of connectors can be used to receive the I2S signal, including LAN (RJ-45), BNC and even HDMI. In fact, this connector plays the role of another digital audio input. Specifically, the I2S standard, on the one hand, is distinguished by good communication quality and noise immunity, on the other hand, it is relatively rare.

— Thunderbolt. A universal digital connector, in this case used to connect a device to a computer. Such connectors are most widely used in Apple technology; accordingly, almost all devices equipped with them are compatible with Mac (see the relevant paragraph).

— FireWire. Also known as IEEE 1394 or i-Link. A universal connector that is similar in functionality to USB, and even surpasses it in some characteristics, but is much less common. It is used to connect to computers and some types of specialized audio equipment.

— Bluetooth. The device supports Bluetooth wireless technology. The main application of this technology in DACs is the wireless transmission of audio from an external Bluetooth device (smartphone, laptop, etc.) to the converter. Initially, such a transfer was associated with a loss of sound quality, but relatively recently, the aptX format has appeared, which allows you to transfer audio via Bluetooth without loss in quality. So when choosing a transducer with Bluetooth, it doesn't hurt to check if it supports aptX (and, of course, this standard must also be supported by the signal source).
In addition to broadcasting sound, there are other options for using Bluetooth — for example, using an external gadget as a remote control. However, they are much less common.

— Wi-Fi. Wi-Fi technology supported by the device. Recall that this technology is mainly used as a way to wirelessly connect to the Internet and local networks. Accordingly, most models with this feature are actually network players capable of playing content from local networks and/or the Internet. The specific capabilities of these devices may vary, some of them are even capable of working with Internet radio stations and audio streaming services. Also, Wi-Fi can be used for direct communication with other devices such as smartphones or tablets, but such use is practically not found among DACs.

— Connecting an iPod/iPhone. The presence in the device of special tools for working with portable gadgets from Apple — primarily iPod players and iPhone smartphones. Usually, in such models, the possibility of a wired connection through a standard 8-pin Lightning connector is provided. In addition, the software part may include special functions for integration with the "apple" gadget. But the ways of using such a connection can be different. For example, in a DAC (see "Type"), the iPhone or iPod serves as a source of digital audio, which is converted by the converter and output to the speakers. And audio interfaces with this function are actually adapters for various musical instruments: the sound from the instrument is processed by the interface and digitally transmitted to the gadget for recording and further processing using the built-in software.

— Mac support. Compatibility of the device with computers and laptops from Apple running the proprietary Mac OS X operating system. Such computers have their own specific features and requirements for peripherals, so for guaranteed compatibility, you should choose equipment that originally claims Mac support.

— Phantom power. The presence of phantom power in the device. Such a power supply, with a nominal voltage of 48 V, is necessary for the operation of certain types of microphones — in particular, condenser ones. Accordingly, the presence of this function means compatibility with similar types of microphones — an important feature, given that many high-end studio-level microphones are made specifically with condensers. Phantom power is found only among audio interfaces (see "Type").

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.