Denon AVR-X3400H and Onkyo TX-NR686 have 7 channel amplifiers. Denon AVR-X3400H delivers 105 W (8 Ω, 20 Hz - 20 kHz, 2 channel driven) and Onkyo TX-NR686 delivers 100 W (8 Ω, 20 Hz - 20 kHz, 2 channel driven) and they both have stable performance at 4 Ω load. Since 2016 all receiver manufacturers have dropped front wide channel support and these models are no exceptions.
Both receivers support 4K passthrough up to 60p. Denon AVR-X3400H can do 4K upscaling up to 60p. The receivers support HDR10, Dolby Vision.
High-dynamic-range (HDR) video has greater dynamic range than standard-dynamic-range (SDR) video with brigter whites and deeper blacks. HDR10 was announced on August 27, 2015, by the Consumer Technology Association and uses the wide-gamut Rec. 2020 color space. It sends static metadata via video stream to the TV which calibrates its screen brightness and color according to that. HDR10 supports up to 1000 nits of brightness and 10-bit color which corresponds to 1024 shades of the primary RGB colors.
Dolby Vision is an update to HDR10 by adding dynamic metadata that can be used to more accurately adjust brightness levels up to 10,000 nits maximum brightness on a scene-by-scene or frame-by-frame basis and supports up to 12-bit color depth (4096 shades of RGB) and 8K resolution.
Dolby Atmos and Dolby Surround upmixer
Denon AVR-X3400H and Onkyo TX-NR686 support Dolby Atmos with its Dolby Surround upmixer. They can be configured upto 5.1.2 channels using internal amplifiers.
Dolby Atmos is the first cinematic audio format in which sounds exist as individual entities, called audio objects. In Dolby Atmos, any sound - the helicopter, a car screeching around a corner, a melodic bird call - can exist as an independent audio object, free of channel restrictions. They can be precisely placed and moved anywhere in your room, including overhead, to flow above and around you in three-dimensional space. Through the use of audio objects, overhead sound, and all the richness, clarity, and power of Dolby sound, Dolby Atmos turns your room into an amazing place for entertainment. You'll feel like you're inside the action, in ways you've never experienced before.
Dolby Atmos for the home represents every sound in the original cinema mix as an audio object. Extensions to the Dolby Audio™ codecs, along with an advanced scalable algorithm, allow Dolby Atmos to be delivered via Blu-ray Disc and streaming media. A spatially-coded substream is added to Dolby TrueHD or Dolby Digital Plus. A Dolby Atmos audio/video receiver (AVR) adapts the cinema experience to your home theater from seven speakers to as many as 34 in 24.1.10 configuration, recreating the original artistic concept. The format supports up to 128 simultaneous independent audio objects in a mix for rich, realistic, and breathtaking sound. It recreates the director's original concept through descriptive metadata to provide customized playback for home theater and delivers sounds above you through overhead speakers, special upward-firing Dolby Atmos speakers, or a Dolby Atmos enabled sound bar.
If the content is not mixed in Dolby Atmos then the Dolby surround upmixer will expand the audio to all channels including ceiling speakers. The upmixer has replaced the Dolby Pro Logic II family with improved upmixing algorithms.
DTS:X and Neural:X upmixer
Denon AVR-X3400H and Onkyo TX-NR686 support DTS:X with its Neural:X upmixer. Both of them can be configured upto 5.1.2 channels using internal amplifiers.
A technique used in DTS:X is similar to the one used in Dolby Atmos. Instead of a fixed number of channels, DTS:X defines object locations from the listener in polar coordinates. An a/v receiver then dynamically renders sound according to the current speaker configuration. The speaker layout employed by DTS:X is the sum of Dolby Atmos and Auro-3D. It has standard 7.1 channel base layer, a 5 channel height layer above the base layer on the front and side walls, and 3 rows of speakers on the ceiling.
DTS Neural:X is an upmixer that can take non DTS:X content and upmix it to the DTS:X speaker layout. It has replaced the DTS Neo family with improved flexibility.
Dynamic Audio Amplification
Onkyo TX-NR686 features Dynamic Audio Amplification which is Onkyo’s amplification philosophy that focuses on capturing the energy and dynamism contained in the audio signal and reproducing it without loss. Audio signals are not static like a test tone, but rather a countless collection of constantly moving waves. While static measurements such as S/N ratio and Total Harmonic Distortion are important, Onkyo believes that excellent dynamic and transient response is the key to emotionally involving sound. Dynamism - the “life” in music - is achieved when the amp can respond to changes in the signal instantaneously, so notes start and stop naturally and the nuances in attack, decay, sustain, and release are voiced with conviction. Onkyo home theater receivers represent the culmination of almost 70 years’ experience in amplifier design. The unique elements of their amplification system comprise high-current, low-impedance architecture to accurately control large speaker cones while enabling instantaneous response to dynamic changes, and discrete wide-range amplifier circuit topology to eliminate phase shift for clear and accurate audio imaging.
Onkyo TX-NR686 is THX™ certified which offers optimal performance, superior quality and seamless integration. THX works with partners from the ground up, so that certified products deliver professional quality audio-visual experiences right out of the box. They only certify the very best products with uncompromised quality, performance and consistency. They ensure that THX certified devices play well with lower performing devices and components. THX listening modes make the receiver to have one speaker set up for movies, music and games. They are tested for power output, bass management, signal-to-noise ratio and feature RE-EQ, timbre matching, boundary gain compensation and THX Loudness Plus.
Advanced Music Optimizer
Compressed music enhancement in Onkyo TX-NR686 is done by Onkyo’s Advanced Music Optimizer. While MP3 or AAC files may sound fine through the headphones of your portable digital player, the limitations of these files can be exposed when played back through a quality home entertainment system. This is because a significant amount of high-frequency bit information is lost during the file-compression process. To counter this, Onkyo has designed the Advanced Music Optimizer to compensate for lost bit information and improve the quality of compressed audio signals. This results in a clearer and more expansive sound. Also included in this technology is a loudness correction feature that further improves the audio character of compressed files.
Phase-Matching Bass Boost
Onkyo TX-NR686 features Phase-Matching Bass Boost. The negative effects of phase-shift or the timing difference between sound waves of different frequencies can sometimes be heard in audio players when corners are cut in order to increase bass response. While most audio systems have some form of low-frequency enhancement system, often a bigger bass sound comes at the expense of mid-range clarity, and results in a smeared or muddy sound. Onkyo’s Phase-Matching Bass Boost technology avoids this problem by improving the phase timing to preserve the natural clarity of the mid-range allowing vocals and strings to shine while maintaining a smooth, powerful bass response at all volume levels.
Denon AVR-X3400H can be connected to internet using ethernet cable or built-in wi-fi adapter. It can also connect to bluetooth devices via built-in bluetooth adapter. The Receiver works with Amazon Alexa and supports[y] AirPlay 2. It has 8 HDMI inputs with HDCP 2.2 copy protection. There are 7.2 channel analog pre-outs for external amplification.
Front panel has HDMI and USB inputs.
Onkyo TX-NR686 can be connected to internet using ethernet cable or built-in wi-fi adapter. It can also connect to bluetooth devices via built-in bluetooth adapter. The Receiver works with SONOS and supports[y] AirPlay 2 after firmware update. It has 7 HDMI inputs with HDCP 2.2 copy protection. There is a phono input with built-in phono stage for connecting the cartridge output of the turntable directly to the Receiver.
Front panel has HDMI and Mini-Jack inputs.