Comparison Onkyo TX-NR686 vs Sony STR-DN1080

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 audio receiver supports eARC, an enhanced version of the Audio Return Channel (ARC) used with an HDMI connection (see below).

By itself, the audio return channel allows you to "swap" the HDMI output of the AV receiver and the HDMI input of the TV or other external device — thus, this device turns into an audio signal source, and the receiver starts to work as a receiver. Such functionality is designed mainly for those cases when the TV receives a signal not from the receiver, but from another source (built-in tuner, media player, flash drive, etc.), however, the soundtrack must be output to external speakers through the receiver. Without ARC, you would have to use an additional connection (for example, via an optical interface), while the audio return channel eliminates the need for extra wires: the same HDMI cable is used both for transmitting video / audio from the receiver to the TV and for transmitting audio from TV to receiver. Also, the advantages of ARC over traditional audio interfaces are higher bandwidth, as well as the ability to use the CEC function (control of connected devices from one remote control).

Specifically, eARC was introduced simultaneously with the HDMI 2.1 standard and received a number of improvements compared to conventional ARC. Here are the main ones:

— Up to 40x more bandwidth, allowing uncompressed 5.1 and 7.1 surround sound, HD audio and Dolby Atmos and DTS:X "object-orie...nted" multi-channel codecs (see Decoders).
— Technology Lip Sync Correct, eliminating desynchronization between video and sound.
— Proprietary protocol to automatically detect audio formats supported by both connected devices and select the best option.

Of course, in order to use eARC, both the receiver and the TV it is connected to must support it.

Receiver support for HDR technology; this clause may also specify the specific supported HDR format.

HDR stands for High Dynamic Range. This technology allows you to expand the range of brightness reproduced simultaneously on the screen; to put it simply, the viewer will see brighter whites and darker blacks. In practice, this means a significant improvement in color quality: colors are more vibrant and at the same time more faithful than without HDR. However, to use this function, in addition to the receiver, a TV/projector that supports the appropriate HDR format and content recorded in this format is required.

In terms of specific formats, the most popular options these days are basic HDR10, advanced HDR10+, and high-end Dolby Vision. Here are their features:

- HDR10. Historically the first of the consumer HDR formats, less advanced than the options described below but extremely widespread. In particular, HDR10 is supported by almost all streaming services that provide HDR content at all, and it is also common for Blu-ray discs. Allows you to work with a color depth of 10 bits (hence the name). At the same time, devices of this format are also compatible with content in HDR10 +, although its quality will be limited by the capabilities of the original HDR10.

- HDR10+. Improved version of HDR10. With the same color depth (10 bits), it uses the so-called dynamic metadata,...which allows transmitting information about the color depth not only for groups of several frames, but also for individual frames. This results in an additional improvement in color reproduction.

Dolby Vision. An advanced standard used particularly in professional cinematography. Allows you to achieve a color depth of 12 bits, uses the dynamic metadata described above, and also makes it possible to transmit two image options at once in one video stream - HDR and normal (SDR). At the same time, Dolby Vision is based on the same technology as HDR10, so in modern video technology this format is usually combined with HDR10 or HDR10+.

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 lowest impedance of the loudspeakers of the speaker system, with which the amplifier is able to work normally. The nominal impedance of the speakers, also referred to as the term "impedance", is one of the key parameters in the selection of audio system components: for normal operation, it is necessary that the speaker impedance match the characteristics of the amplifier. If the speaker impedance is greater, the sound volume will decrease significantly, if it is less, distortion will appear in it, and in the worst case, even overloads and breakdowns are possible. Therefore, in the characteristics of receivers, it is usually the minimum resistance that is indicated — after all, connecting a load of too low impedance is fraught with more serious consequences than too high.

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.

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.).