Comparison Rotel RCD-1572 vs NAD C568

The model of the digital-to-analogue converter (DAC) installed in the CD player.

The DAC is one of the most important components of any modern CD player. It is this module that is responsible for converting digital data recorded on an optical disc into an analogue audio signal that is fed to an external device (amplifier, speakers, etc.). Accordingly, the characteristics and overall quality of the DAC largely determine the sound quality in general. Knowing the DAC model, you can find detailed data on it — characteristics, reviews, test results, etc. — and evaluate how the capabilities of the converter meet your requirements.

The audio file formats that the player can handle. This list includes popular formats MP3, WMA, AAC, OGG, WAV, FLAC, but is not exhaustive.

— MP3. The most famous of modern digital audio formats; supported by almost all devices. Provides so-called. lossy compression, where some of the audio frequencies are lost. However, during compression, the sound is processed in such a way that it "disappears" mainly frequencies, the loss of which is imperceptible to the human ear.

— WMA. An audio format that was once specially created for the Windows operating system. The default is lossy compression. WMA is especially suitable for low bitrates, under such conditions it provides better quality than MP3 and takes up less space. On the other hand, in high-quality digital audio, this format is much less popular.

— WAV. Another popular audio standard, originally developed for storing sound on a PC. It can technically be used to store audio in a variety of formats, but is most commonly used for uncompressed audio. Due to this, the sound quality can be quite high, and its processing does not require special computing power. The downside of this is the large volume of audio files — many times more than MP3s.

— AAC. A format d...eveloped as a potential successor to MP3. Also provides lossy compression (see above), but allows you to achieve better quality with the same file size; this difference is especially noticeable at low bitrates. Actively promoted by Apple; nevertheless, it is noticeably inferior to MP3 in terms of prevalence.

— OGG. A lossy compressed digital audio format is one potential alternative to MP3. One of the key features of OGG is that as audio is encoded, the bitrate is constantly changing; at the same time, on fragments where there is no sound, the bitrate drops to almost zero (unlike MP3, where the data stream is constant, including in sections of complete silence). This allows you to achieve small file sizes while maintaining sound quality. Also note that the OGG format is open and not limited by patents.

— FLAC. One of the formats that uses lossless audio compression. With this compression, all the details of the original sound are preserved, so lossless formats are especially appreciated by sophisticated music lovers and audiophiles. The reverse side of this quality is large volumes of files. Specifically, FLAC is perhaps the most common of today's lossless formats. This is largely due to the fact that this standard is not particularly demanding on the processing power of the player. Thanks to this, its support can be implemented even in relatively simple and inexpensive players (unlike another popular format — APE, see below). On the other hand, FLAC files are larger than APE files.

— A.P.E. One of the popular lossless audio compression formats. Compared to another common standard — FLAC (see above) — APE allows you to achieve smaller file sizes with the same quality. On the other hand, to play such files, electronics with a fairly high processing power are required, so APE compatibility is relatively rare in compact players.

This list

Wired and wireless interfaces for connecting external devices provided in the design of the CD player.

— Airplay. A technology for transmitting multimedia data over a Wi-Fi wireless connection (see below). Developed by Apple and widely used in its portable devices, in particular the iPod touch, iPhone and iPad, but is also available for equipment from other manufacturers. Allows you to broadcast audio files to compatible devices (in streaming audio mode, see "Playback" for details), as well as images, text data, and even video. The presence of AirPlay in a CD player will make it possible to connect devices supporting this technology to it for direct playback, as well as display information about files — song title, artist name, etc.

— Wi-Fi. A wireless interface that can be used for two purposes: connection to computer networks (including the Internet) and direct connection with smartphones, tablets and other external equipment. The first option is convenient for implementing network functions — streaming audio, Internet radio(see "Playback"), AirPlay (see above), DLNA(see below). Connection to computer networks can also be carried out through a wired LAN interface (see below), however, Wi-Fi is more convenient due to the lack of wires and the ability to wor...k through obstacles (including walls) at a distance of several tens of metres. And connection with external devices can be provided primarily for remote control of the player.

— Bluetooth. A wireless technology developed for the direct communication of various devices with each other. Provides a distance of up to 10 m (in specific cases — and more, but this option is not relevant for CD players). Specific Bluetooth capabilities may vary depending on the protocols supported by the device. In the case of players, this function is usually used to broadcast audio to wireless headphones or Bluetooth speakers; this connection is convenient due to the absence of a wire, but the sound quality can be noticeably lower than with a wired connection. The reverse option may also be provided — broadcasting sound from a smartphone, tablet, etc. for playback through the player and acoustics connected to it; but this application, like others, is extremely rare.

— LAN. A standard interface used for wired connection to computer networks — both to "local computers" (with or without Internet access), and directly to Internet providers. Accordingly, the presence of such a connector in a CD player implies support for network functions — for example, DLNA or Internet radio (see "Communications"); specific networking capabilities vary by model.

— RS-232. It's a COM port. A specialized connector used to connect the player to a computer and control its settings from a PC. Such control can be more diverse and at the same time simpler and clearer than working with a standard panel or remote control.

— DLNA. A technology used to connect various electronic devices into a single digital network with the ability to directly exchange content. Devices for which support of this standard is claimed are able to interact effectively regardless of the manufacturer. A DLNA CD player can, for example, play music from a computer hard drive in the next room. Connection to the Network can be carried out both wired (LAN) and wireless (Wi-Fi) way; both options are described above.

— USB (type A). This connector is used to connect various USB peripherals to the device. In the case of CD players, we are most often talking about "flash drives" and other external drives: when they are connected to USB Type A, direct playback of the content recorded on such a drive is possible. Usually, this connector is installed on the front panel of the player, and some models of connectors may have more than one.

— USB (type B). This interface allows you to connect a CD player to your computer as a peripheral device. Such a connection can provide a wide variety of possibilities: playback of sound from a PC through the player and acoustics connected to it, control of the player's settings through the service programme, firmware updates, etc. (the specific set of capabilities depends on the model).

— Card reader. A slot for reading memory cards — most often the most popular modern SD format, although theoretically other options can be provided. This feature allows you to play music directly from memory cards. Such media are convenient because card readers are installed in almost all modern laptops, many tablets, smartphones (albeit for smaller cards), etc. However it must be borne in mind that even among SD cards there are several generations that are incompatible with each other; therefore, before using a card reader, you should definitely clarify which cards it is designed for.

— Connecting an iPod/iPhone. The presence in the CD player of special functions for working with portable Apple devices — iPod players, iPhone smartphones, and in most cases — iPad tablets. Such functions may include, for example, switching tracks on the player and managing playlists from the player's remote control; anyway, they make life much easier for those who would like to listen to music from the "apple" technology. Note that in the case of CD players, to connect such equipment, it is usually not a special dock that is used, but a regular general-purpose USB type A port (see above), with which the device is connected via a special cable. Occasionally there are models equipped with external docking stations (which, however, are most often also connected via USB).

The range of audio frequencies that a CD player can reproduce. In general, this parameter determines how full the output bandwidth is, whether too high or too low sound is cut off. However, it is worth noting here that the human ear is able to perceive sound only within the range of 16 – 20,000 Hz (deviations from the upper threshold in different directions are possible, but small, and it decreases with age). All modern CD players cover this range, therefore, in the case of such devices, the sound frequency indicators are reference and practically do not affect the sound. And impressive numbers like 2 – 40,000 Hz, 5 – 60,000 Hz, etc. — this is a kind of "side effect" of the design of a high-quality device; manufacturers use these numbers for marketing purposes, but again, they do not affect sound quality. Also, do not forget that actually audible frequencies are also limited by the characteristics of the speaker system, external amplifier and other equipment connected to the CD player. For example, speakers with a lower frequency range of 150 Hz will “cut off” all lower frequencies, and it doesn’t matter what the lowest bass the player can produce is 16 Hz, 20 Hz or 50 Hz.

The dynamic range of a CD player.

Technically, dynamic range is the logarithm of the ratio between the maximum input signal at which the level of distortion is low enough (tolerable) and the sensitivity of the amplifier. In a simplified way, this parameter can be described as the difference between the minimum and maximum sound levels that the device is capable of reproducing with high quality. The higher the dynamic range value, the better the device handles with sound that has significant volume differences, such as orchestral parts.

Note that when playing different sound standards (see "Playback"), the dynamic range of the player will also be different — for example, for SACD its value is usually much higher than for Audio CD. CD players typically list the highest value that gives the best impression of the device's performance. However, manufacturers often specify for which type of digital audio the dynamic range data is given.

The coefficient of harmonic distortion (harmonics) output by the CD player.

This parameter, along with the signal-to-noise ratio described above, characterizes the overall sound quality of the player. It is calculated by dividing the total sum of harmonics by the value of the main signal at a reproduced sound frequency of 1 kHz, and is expressed as a percentage. Significant levels of harmonics lead to deterioration in sound — from a general feeling of "roughness" and "excessive density" of the sound to the appearance of clearly audible noise; accordingly, the lower the harmonic distortion, the better. In relatively inexpensive CD players, this figure is measured in tenths of a percent, in top models it may not exceed several thousandths of a percent.

Outputs provided in the design of the CD player (in addition to analogue connectors for connecting general-purpose acoustics — they are described in separate paragraphs below).

— Coaxial S / P-DIF. Interface for transmitting sound in digital format. Allows you to work with multi-channel audio up to 7.1 format inclusive. Technically an electrical variation of S/P-DIF; differs from the optical variety described below, on the one hand, by greater sensitivity to electromagnetic interference, and on the other hand, by a less delicate connecting cable. Note that this interface uses RCA connectors and a coaxial cable (hence the name). However, unlike "regular" analogue RCA (see below), in this case, all audio channels are transmitted over a single cable, and the cable itself must be shielded — when connected through a regular wire, there is a high probability of distortion due to external interference.

— Optical. A modification of the S/P-DIF standard (see above), which involves signal transmission via a TOSLINK fiber optic cable. Being identical to the coaxial interface in terms of audio transmission capabilities, the optical connection is at the same time completely immune to electromagnetic interference, which makes it possible to achieve extremely high signal fidelity. The disadvantage of this connection is the fragility of the cable — it does not allow sharp bends and strong pressure, whic...h can damage the fiber.

— Balanced digital (AES/EBU). The AES / EBU standard itself can use different connection interfaces, however, XLR connectors are usually used in audio equipment. However, unlike the "regular" XLR output (see below), this interface transmits audio in digital format, not analogue. A common feature of these standards is a balanced connection, which provides noise suppression due to the characteristics of the cable itself, has a positive effect on sound quality and at the same time allows the use of fairly long wires. AES/EBU is considered a professional interface; such an output can be useful, for example, for connecting a CD player to a high-end external amplifier.

— Trigger. A service output used to turn on other components of the audio system (for example, an amplifier) at the same time as a CD player. When the player is turned on, this output sends a signal to the input of the controlled device and wakes it up, saving the user from having to press extra buttons. This is especially useful if the device being controlled is located in a hard-to-reach place.

— Headphones. Output for connecting conventional audio headphones. There is no single standard for such a connector, however, the vast majority of both players and “ears” use one of the varieties of the Jack type connector — full-size 6.35 mm or mini-Jack 3.5 mm. At the same time, in stationary audio equipment, including CD players, the full-size version is quite common, but 3.5 mm plugs are very popular in headphones — they can be connected both to the “native” jack and to the 6.35 mm jack, through a simple adapter (many models even come with adapters. Anyway, the ability to listen to music through headphones will be useful in cases where loud sounds are undesirable — for example, at a late time when others are sleeping, or if there is a small child in the house.

— Subwoofer. Separate output for connecting an active subwoofer — a specialized low-frequency speaker with its own built-in amplifier. The need to use subwoofers is due to the fact that general-purpose speakers do not cope well with low frequencies, as well as some acoustic features of these frequencies. And a dedicated output for such a speaker greatly simplifies the connection: this output is supplied with a filtered low-frequency signal, so you can do without crossovers and other external equipment (the only exception is a passive subwoofer, which will require an external amplifier for this connection).

— Control output (IR). Auxiliary output used in remote control systems. With this connector, the CD player's built-in IR receiver can be used to control other audio system components from the remote control, such as an amplifier in another room, out of range of the remote control. In fact, the player in such cases plays the role of a remote sensor, receiving commands and transmitting them through the control output to another device. Note that the very presence of control inputs and outputs does not guarantee the compatibility of various devices, especially if they are produced by different manufacturers; the nuances of sharing should be clarified according to the official documentation.

— BNC. By itself, BNC is a type of connector related to coaxial; similar in size to RCA, but differs in internal dimensions and mounting features. In CD players, a connector with such an output can be used both for outputting digital sound, similar to coaxial SP-DIF, and for working with special equipment for synchronizing digital sound pulses. The specific use case should be specified separately, there are both at once. Note that in the second case, the BNC output is responsible for switching the synchronization signals received by the CD player from an external clock generator to other devices in the audio system. For more information about synchronization, see "Inputs — BNC".

— Power output. This output is a power connector installed directly on the body of the player. From such a connector, you can power another component of the audio system — for example, an external amplifier or active acoustics; in some cases, this may be more convenient than connecting such components to the network separately. Please note that power plugs are usually different from standard 230 V sockets and are not compatible with plugs for such sockets.

Like the RCA described above, the XLR connector itself is used in different interfaces, and it also has several varieties that differ in the number of pins. However, here we are talking specifically about a three-pin connector used to transmit an analogue audio signal to an external amplifier. In terms of application and some features, such an interface is similar to the mentioned RCA — in particular, two connectors are required to transmit stereo sound, so a pair of jacks is considered one output. However, XLR is more advanced and is suitable even for high-end professional audio equipment — in particular, due to the fact that it provides a balanced connection, in which the cable acts as an interference filter and does not degrade the sound even at a fairly long length. Therefore, the presence of such connectors is typical for premium CD players. Note that even in such models, more than one pair of XLR connectors is usually not installed — it is believed that one output is enough.

The power consumed by the CD player. Usually, unless otherwise noted in the notes, this refers to the power during normal operation. Note that the actual power consumption at a particular point in time may differ from this indicator — for example, when a model with its own power amplifier (see "Built-in amplifier") is operating at low volume or vice versa, when playing a song with sudden volume jumps. However, when organizing the power supply of the audio system, it is necessary to focus on this indicator.

Note that the power consumption cannot be lower than the power of the built-in amplifier (if present, see above). However, some manufacturers may go for tricks — for example, indicate power consumption only in preamplifier mode. As a result, the power consumption stated in the specifications is significantly lower than the actual value when the amplifier is turned on (and sometimes even lower than the rated power of the amplifier alone). In such cases, the actual power consumption can be estimated by adding the claimed power consumption to the power of the amplifier and taking a margin of 20 – 30% for energy losses due to non-perfect efficiency of electronic circuits. For example, for a 50 W model with a 2x60 W amplifier, this value will be about 200 ... 220 W (50 + 2x60 \u003d 170, plus a loss correction).