Denon AVR-X4400H has 9 channel and Yamaha RX-V685 has 7 channel amplifiers. Denon AVR-X4400H delivers 125 W (8 Ω, 20 Hz - 20 kHz, 2 channel driven) and Yamaha RX-V685 delivers 90 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. They both 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-X4400H and Yamaha RX-V685 support Dolby Atmos with its Dolby Surround upmixer. The Denon AVR-X4400H can be configured upto 7.1.2 or 5.1.4 channels using internal amplifiers or upto 7.1.4 channels by adding 2 channel external amplifier and the Yamaha RX-V685 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-X4400H and Yamaha RX-V685 support DTS:X with its Neural:X upmixer. The Denon AVR-X4400H can be configured upto 7.1.2 or 5.1.4 channels using internal amplifiers or upto 7.1.4 channels by adding 2 channel external amplifier. The Yamaha RX-V685 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.
Auro-3D with its Auro-Matic upmixer
Denon AVR-X4400H supports Auro-3D and its Auro-Matic upmixer out of the box or after free firmware update. Auro-3D is an immersive 3D audio format developed by the Belgium-based company Auro Technologies. It consists of three layers of sound - surround, height and overhead ceiling. The base horizontal layer uses 5.1 or 7.1 format, the height layer is on top of the base layer and its information is extracted from the standard 5.1 surround PCM carrier. The a/v receiver decoder then extracts this information during playback. In home cinema Auro-3D comes with different listening formats - Auro 9.1, Auro 10.1 with added Top Ceiling channel ("Voice of God"), Auro 11.1 with added Front Height Center channel, and Auro 13.1 with added Left Rear Surround & Right Rear Surround channel. Auro-Matic upmixer takes non Auro-3D sound and upmixes to the current speaker configuration.
Yamaha RX-V685 features Adaptive DRC (Dynamic Range Control) which automatically adjusts the dynamic range of the sound according to the volume level. This ensures that you hear clear dialog and vocals, and all sound effects at comfortable levels. There is no need to adjust the volume level as you listen; everything from whispers to big explosions will be heard clearly and comfortably at the same volume setting. It also tones down loud TV commercials, and is ideal for low-volume, late-night listening, when you do not want to disturb others.
Denon AVR-X4400H has D.D.S.C (Dynamic Discrete Surround Circuit). A single IC chip is generally used in processing A/D, DSP, and D/A conversions that are vital to sound quality. The D.D.S.C. uses separate components to process the important sections of the A/D, DSP, and D/A conversions and therefore significantly improves signal processing capability and performance. In addition, the approach of developing and incorporating high-quality dedicated elements in the sections that configure the circuitry makes it easier to develop a high-grade, advanced surround circuit compared with the method where all processing is concentrated within a single chip. Denon’s proprietary digital audio technology that had for many years been developed for pure Hi-Fi components is now also alive in each block of the D.D.S.C.
Advanced AL32 Processing
Denon AVR-X4400H has Advanced AL32 Processing which uses a unique data interpolation algorithm to achieve high-bit, high-sampling output performance. The volume of information has been dramatically improved without any loss in the original data. The clean playback sound free of interference makes it possible to enjoy delicate details, accurate localization, and rich expression in the lower range. Advanced AL32 Processing has three functions: 1. High-bit up-conversion (Adaptive Line Pattern Harmonized Algorithm), 2. Advanced ALPHA Processing and 3. Adaptive digital filter (Automatic Low-Pass filter Harmonic Adjustment).
Denon AVR-X4400H 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 is a phono input with built-in phono stage for connecting the cartridge output of the turntable directly to the Receiver. There are 11.2 channel analog pre-outs for external amplification.
Front panel has HDMI, USB, Composite and L/R Audio inputs.
Yamaha RX-V685 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 via firmware update. It has 5 HDMI inputs with HDCP 2.3 copy protection. There is a phono input with built-in phono stage for connecting the cartridge output of the turntable directly to the Receiver. There are 2.2 channel analog pre-outs for external amplification.
Front panel has USB and mini-jack Audio inputs.