Comparison Onkyo TX-NR646 vs Onkyo TX-NR626

A digital-to-analogue converter (DAC) is an indispensable element of any system designed to reproduce digital sound. The DAC is an electronic module that translates sound information into pulses that are sent to the speakers. The technical features of such a conversion are such that the higher the sampling frequency, the better the signal at the output of the DAC, the less it is distorted during conversion. The most popular option in receivers today is 192 kHz — it corresponds to a very high sound quality (DVD-Audio) and at the same time avoids unnecessary increase in the cost of devices.

Another indicator that determines the overall quality of the digital-to-analogue audio converter. For details on the converter, see "Audio DAC Sampling Rate"; here we note that the bit depth is standardly expressed in bits, and the higher it is, the more accurately the signal at the output of the DAC corresponds to the original signal and the less distortion is introduced into it. Today, it is believed that a 16-bit indicator provides quite acceptable signal quality, and 24-bit DACs are suitable even for premium-level equipment.

Possibility to simulate multi-channel (for example, 5.1) sound in traditional two-channel headphones. For this, a Dolby Headphone decoder is usually used, which processes the sound in such a way that the sound heard in the headphones is perceived as multi-channel — in particular, the intended position of its sources can be determined much more accurately. And considering that modern Hi-Fi class headphones are not inferior in sound quality to acoustics (and are significantly cheaper), this feature may well come in handy even for demanding audiophiles.

The ability to increase the resolution of the video signal processed by the receiver - if the original video resolution is lower. Depending on the capabilities of the receiver, in particular its HDMI ports, upscaling to Ultra HD 4K and upscaling to Ultra HD 8K may occur.

The principle of upscaling is that a relatively low-resolution video is supplemented with the required number of pixels using special algorithms. Due to this, when playing such a video, the quality of the “picture” is noticeably higher than without upscaling (although somewhat lower than that of content originally recorded in UltraHD). It makes sense to specifically look for a receiver with this function if you plan to use it with a 4K or 8K screen.

This indicator determines the amount of extraneous noise that accompanies the sound output by the receiver's amplifier. It is convenient because it takes into account almost all possible significant noise — both created by the device itself and due to external causes. The higher the signal-to-noise ratio, the lower the noise volume compared to the main signal, the cleaner the amplifier will sound. A reading of 70-80 dB is considered normal for most consumer electronics, but in AV receivers, which are usually premium devices, this can only be called satisfactory. In the most advanced models, this figure can significantly exceed 100 dB.

The range of sound frequencies that the receiver is capable of outputting (this parameter can also be specified for models without their own amplifier, see “Number of channels” for more details). The completeness of the transmitted sound depends on this parameter; of course, the sound quality in general is highly dependent on a number of other factors (for example, frequency response), but the wider the frequency range, the less risk that the amplifier will completely “cut off” some part of the sound. On the other hand, it should be taken into account here that the normal hearing range of the human ear is approximately 16 – 20,000 Hz, and deviations from these limits are rather small. And although many modern receivers provide a much wider frequency range, however, this is more of a marketing ploy than a really significant indicator (or some kind of "side defect" in the design of a high-quality amplifier).

It is also worth considering that in order to reproduce the full frequency of the amplifier, you will need speakers with the appropriate characteristics.

Audio and video file formats that the receiver is capable of playing on its own. Models with player features generally support most popular media file types (particularly AVI, MPEG and MKV for video, MP3, WAV and WMA for audio), but the file set may have its own peculiarities. This item allows you to find out.

- AirPlay. Technology for transmitting multimedia data via a wireless connection ( Wi-Fi). Developed by Apple, it is intended mainly for broadcasting content from various Apple devices (primarily portable gadgets) to compatible external devices. Allows you to transfer audio files (in audio streaming mode, see “Tuner and playback” for more details), as well as images, text data and even video. The presence of AirPlay in the receiver will allow you to connect Apple equipment with support for this technology to it for direct playback, as well as display information about files on an external screen (for example, a TV) - song name, artist name, etc.

- AirPlay 2. The second version of the AirPlay technology described above, released in 2018. One of the main innovations introduced in this update was support for the multi-room format - the ability to simultaneously broadcast several separate audio signals to different compatible devices installed in different locations. Thus, you can, for example, turn on the next episode of your favorite series from your iPhone on the TV in the living room, and relaxing music from your iPod in the kitchen, etc. In addition, AirPlay 2 received a number of other improvements - improved buffering, the ability to stream to stereo acoustics, as well as support for voice control via Siri.

- Chromecast.... Original name: Google Cast. Technology for broadcasting content to external devices, developed by Google. Allows you to transmit video and audio from a PC or mobile device to the AV receiver; broadcasting is usually carried out via Wi-Fi, while the receiver and the signal source must be on the same Wi-Fi network (with the exception of Chromecast media players). Chromecast technology supports two modes - actual broadcasting through special applications (available for Windows, macOS, Android and iOS) and “mirroring” content opened in the Google Chrome browser on an external screen.

- Wi-Fi. A wireless interface used primarily for building computer networks. Accordingly, AV receivers may need its presence primarily to implement network functions - streaming audio, Internet radio (see “Tuner and playback”), AirPlay (see above), DLNA (see below). Connecting to computer networks can also be done through a wired LAN interface(see below), but Wi-Fi is more convenient due to the absence of wires and the ability to work through obstacles (including walls) at a distance of several tens of meters. In addition, in some models, this technology can also be used to communicate directly with other devices - for example, to use a smartphone or tablet as a remote control, or to broadcast live video using Miracast technology or another similar format.

— Bluetooth. Direct wireless communication technology between various electronic devices; operates at a range of about 10 m, although some specific operating formats provide a longer range. Technically, it can be used for different purposes, depending on the protocols supported by a particular device; In AV receivers, two protocols are most often found - A2DP for wireless broadcasting of audio signals and AVRCP for remote control. In the first case, we are usually talking about transmitting a signal from an external device (smartphone, laptop, etc.) to the receiver; theoretically, the opposite option is also possible - broadcasting sound to Bluetooth headphones or acoustics, however, for a number of reasons, this format of operation is almost never found in AV receivers. AVRCP, in turn, allows you to use an external gadget (for example, the same smartphone) as a remote control.

- LAN. A standard interface for wired connection of various equipment (including AV receivers) to computer networks, incl. to access the Internet. Due to the presence of a wire, it is less convenient to connect than the Wi-Fi described above. On the other hand, a LAN connection wins in terms of connection reliability and actual data transfer speed - especially if there are many wireless devices on the network and Wi-Fi channels are busy (which is often the case, since Wi-Fi modules are very popular in modern electronics ). Therefore, for working with large volumes of data - for example, watching high-definition video via DLNA (see below) - LAN is better suited.

— RS-232. A wired interface that originally appeared in computer technology. In AV receivers, it can be called a service connector: content is not transmitted through this connector, but through it you can connect the device to a computer and remotely change settings, as well as update the firmware.

— MHL. High-speed wired interface for transmitting multimedia data (video and audio) from mobile devices to external screens. The bandwidth allows you to work with high or even ultra-high resolution images, as well as multi-channel audio. Also, when connected, the gadget can be charged. In mobile devices, the MHL signal is output via a standard microUSB port; and the role of the input in AV receivers (and other stationary equipment) is played by the HDMI connector (see below) - however, not every connector, but only one that is initially compatible with MHL and has the appropriate marking. Adapters are available for connecting to regular HDMI, but additional functions (like charging) may not be available with this connection.

- 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 for this standard is declared are able to communicate effectively regardless of the manufacturer. An AV receiver with DLNA can, for example, play a movie directly from the hard drive of a computer in the next room, or transfer photos from a smartphone to the TV. Connecting to the Network can be done either wired (LAN) or wirelessly (Wi-Fi, see above).

- Roon Tested. Roon Tested accreditation means the AV receiver is compatible with the popular audiophile music streaming platform Roon. Certified models have undergone a series of tests and meet the quality standards required to operate Roon flawlessly. This ensures convenient management and organization of content within the platform.

— Coordination of Remote control. A function that allows you to connect the AV receiver to another device (for example, a Blu-ray player or external amplifier) and control both devices with one remote control. When purchasing equipment with such a function, it is necessary to clarify compatibility - as a rule, only equipment from one manufacturer can work in such a “bundle”, and even in such cases, their own nuances are possible upon agreement.

— Voice assistant. Receiver support for voice assistant. The most popular assistants these days are:

• Google Assistant
• Apple Siri
  
• Amazon Alexa

However, other solutions may also emerge. In any case, it is worth noting that we are not talking about an assistant built into the receiver itself, but about compatibility with external devices that have this function (for example, a smartphone or tablet). But even such compatibility allows you to give commands to the receiver by voice - this is often more convenient than more traditional control methods. The specific set of supported commands and languages may vary depending on the voice assistant and its specific version.

A decoder can be broadly described as a standard in which digital audio (often multi-channel) is recorded. For normal playback of such sound, it is necessary that the corresponding decoder is supported by the device. The first signs of multi-channel decoding were Dolby Digital and DTS, gradually improving and introducing new features. The final stage for 2020 is Dolby Atmos and DTS X decoders. And the intermediate ones were Dolby TrueHD, Dolby Pro Logic II, DTS-HD, DTS ES, DTS Neural: X, DTS Neo (6, X).

Dolby Atmos. A decoder that does not use a rigid distribution of sound across channels, but the processing of audio objects, due to which it can be used with almost any number of channels on a reproducing system — the sound will be divided between channels so that each audio object is heard as close as possible to its proper place. When using Dolby Atmos, in-ceiling speakers (or speakers facing the ceiling) are highly desirable. However, in extreme cases, you can do without them.

— DTS X . An analogue of the Dolby Atmos described above, when the sound is distributed not through individual channels, but through audio objects. The...digital signal contains information about where (according to the director's intention) the object audible to the user should be and how it should move, and the processor of the reproducing device processes this information and determines exactly how the sound should be distributed over the available channels in order to achieve the required localization. Thanks to this, DTS X is not tied to a specific number of audio channels — there can be as many as you like, the system will automatically divide the sound into them, achieving the desired sound. Also note that this decoder allows you to separately adjust the volume of dialogues.

— IMAX Enhanced. The IMAX Enhanced Mark of Conformity is awarded to equipment that meets the audio certification requirements of IMAX Corporation. Combined with DTS audio technology to deliver signature IMAX theater-like sound in the home. The most accurate reproduction of such audio is possible in systems with a large number of channels (5.1 or more). Note that for a fully immersive experience, IMAX Enhanced certification must also apply to video equipment for playing content (TV, projector, etc.).