Onkyo TX-NR656 vs Onkyo TX-NR646

Here we are comparing Onkyo TX-NR656 to Onkyo TX-NR646 to reveal their common strengths and weaknesses as well as the differences between them which will help you in making a correct decision before the purchase. Both receivers have 7 channel and equally powerful amplifiers.

Now that we've looked at the most essential specifications and gained a basic understanding of these receivers, we can delve into more details and see the differences between them.

This section shows those features and specifications which are the reason to choose Onkyo TX-NR656 over Onkyo TX-NR646.

This section shows those features and specifications which are the reason to choose Onkyo TX-NR646 over Onkyo TX-NR656.

We already listed pros and cons of each model. However, you may also find useful to look at their common strengths and weaknesses shown side-by-side.

Amplifier

• Dynamic Audio Amplification: Onkyo TX-NR656 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.
• WRAT (Wide Range Amp Technology): Onkyo TX-NR646 features Onkyo’s Wide Range Amp Technology (WRAT) circuit layout that prevents phase shifting by pushing the roll-off point higher than the listening-level frequency. Amplifying sound without phase shift creates an uncommonly well-focused and realistic audio image. If phase shift occurs and signal timing is not accurate, then neither is the resulting audio image.

Speaker Configurations

Onkyo TX-NR656's and Onkyo TX-NR646's amplifiers can be assigned for different speaker configurations.

• Dolby Atmos Configurations: The following speaker configurations are supported for Dolby Atmos:
Onkyo TX-NR656: 5.2.2 with internal amplifier.
Onkyo TX-NR646: 5.2.2 with internal amplifier.
• DTS:X Configurations: The following speaker configurations are supported for DTS:X:
Onkyo TX-NR656: The speaker configurations for DTS:X are the same as for Dolby Atmos - 5.2.2 with internal amplifier.
Onkyo TX-NR646: The speaker configurations for DTS:X are the same as for Dolby Atmos - 5.2.2 with internal amplifier.
• Configurations without height channels: There are also other speaker configurations available which do not include height channels:
Onkyo TX-NR656: 5.2, 7.2 with internal amplifier.
Onkyo TX-NR646: 5.2, 7.2 with internal amplifier.
• 2-ch Bi-Amp: Both models are able to bi-amp up to 2 main channels simultaneously. During bi-amplification two amplifiers are used for one speaker. One amplifier powers the midrange and tweeter section of the speaker and another amplifier powers the low frequency woofers. Each amplifier is less loaded and performs better. In order to use this feature speakers must have 2 pairs of connectors.



Dolby Atmos

Onkyo TX-NR656 and Onkyo TX-NR646 support Dolby Atmos. It is a cinematic audio format in which sounds exist as individual entities, called audio objects. In Dolby Atmos, any sound 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. 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.

• Dolby Surround Upmixer: Both models support Dolby Surround Upmixer. 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

Onkyo TX-NR656 and Onkyo TX-NR646 support DTS:X. 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: Onkyo TX-NR656 supports DTS Neural:X which is an advanced 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.
• DTS Dialog Control: Both models have DTS Dialog Control. This function adjusts the dialog levels during playback of the DTS:X stream. It allows you to separately increase the dialog levels in contrast with the background sound and hear dialog easily even under noisy circumstances.

Sound Processing

• Compressed Music Enhancer: Onkyo TX-NR656 and Onkyo TX-NR646 feature Compressed Music Enhancer which enhances the quality of the music files with lossy compression.
Advanced Music Optimizer: Compressed music enhancement in Onkyo TX-NR656 and Onkyo TX-NR646 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.

Room Calibration

Onkyo TX-NR656 comes with AccuEQ with AccuReflex™ and Onkyo TX-NR646 comes with AccuEQ Advance room correction system.

• AccuEQ: First, AccuEQ detects the presence of speakers and evaluates the impedance of each. Next, it pinpoints their distance relative to the main listening position using the mic and sets suitable sound-pressure levels. Then it selects the optimal crossover frequency so that deeper bass rolls smoothly off to the subwoofer. Finally, AccuEQ performs frequency response equalization based on room-acoustic and speaker data collected via microphone. The sound-field is now tailored around the listening position, resulting in a more immersive and realistic in-film experience.

HDMI

Onkyo TX-NR656 and Onkyo TX-NR646 come with 8 HDMI inputs. It has 2 outputs which work parallelly and output the same signal.

• 4K/60Hz Passthrough: On both receivers all inputs pass up to 4K/60p (RGB/YCbCr4:4:4) video signal.
• 4K Upscaling on Onkyo TX-NR656: It can upscale 1080p to 4K from HDMI and analog sources.
• Analog To HDMI Upconversion: Both receivers support analog to HDMI Upconversion, so you can input your analog video sources and output them digitally via HDMI. This means that you will need only one HDMI cable to connect to your TV.
• BT.2020 Color Space: BT.2020 or Rec. 2020 is a color standard which delivers a wider color gamut compared to Rec. 709. It covers approximately 75% of the total visual spectrum while the Rec. 709 covers only 35% (available on Onkyo TX-NR656 only).
• HDCP 2.2.0 Copy Protection: Both receivers are HDCP 2.2.0 compliant which is a requirement for 4K/HDR copy-protected content transmission.
• 3D Ready: Both receivers are able to pass 3D video through HDMI.

HDR (High Dynamic Range)

Onkyo TX-NR656 supports HDR10 and Dolby Vision.

Onkyo TX-NR646 supports HDR10

High dynamic range video has greater dynamic range than standard dynamic range (SDR) video with brighter whites and deeper blacks. The result is greater contrast and more details in dark and bright areas, better color and depth.

• HDR10: HDR10 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 10-bit color which corresponds to 1024 shades of the primary RGB colors. It is technically limited to a maximum of 10,000 nits peak brightness, however common HDR10 contents are mastered with peak brightness from 1,000 to 4,000 nits.
• Dolby Vision: Dolby Vision is a set of technologies developed by Dolby Laboratories for high dynamic range (HDR) video. It covers content creation, distribution, and playback. Like HDR10+, it includes dynamic metadata that are used to adjust and optimize each frame of the HDR video to the consumer display's capabilities in a way specified by the content creator. Dolby Vision allows for a maximum resolution of 8K up to 12-bit color depth, maximum peak brightness of 10,000 nits and a color gamut up to Rec. 2020. It uses Dolby's proprietary dynamic metadata defined in SMPTE ST 2094-10.

Audio

• Phono Input: There is an MM phono input on Onkyo TX-NR656 and Onkyo TX-NR646 with built-in phono stage for connecting the moving magnet cartridge output of the turntable directly to the receiver.
• Analog Line Inputs and Outputs: There are 7 pair of line inputs on both receivers for connecting sources with analog outputs. There is also 1 pair of line outputs on Onkyo TX-NR646.
• Digital Inputs: 2 optical inputs and 1 coaxial input are available for digital audio connections on both receivers.
• Headphone Output: There is a 6.3 mm (1/4") headphone output jack on the front panel of each receiver.

Video

• HDMI:
Onkyo TX-NR656
Inputs: 8 (1 front)   Outputs: 2 (simultaneous)
8K Inputs: 0.
Onkyo TX-NR646
Inputs: 8 (1 front)   Outputs: 2 (simultaneous)
8K Inputs: 0.
• Composite Video: Connect you VCR, Laserdisc player and other old video equipment with composite video cables.
Onkyo TX-NR656
Inputs: 2   Outputs: 0.
Onkyo TX-NR646
Inputs: 3   Outputs: 0.
• Component Video: Component video connection gives you the higher quality video compared to the composite video connection. So in case your old DVD player and other equipment do not have an HDMI output but have Component video output use this connection over the composite one. Both receivers support up to 480i/576i resolution on Component video connectors.
Onkyo TX-NR656
Inputs: 2   Outputs: 0.
Onkyo TX-NR646
Inputs: 2   Outputs: 0.

Front A/V Inputs

• Onkyo TX-NR656: HDMI, Mini-Jack
• Onkyo TX-NR646: HDMI

Onkyo TX-NR656

Onkyo TX-NR646