Onkyo 7.2 Channel TX-NR646 REVIEW
Onkyo receivers always offer a lot of value. The 646 is no exception. When you combine its number of features with its excellent sound quality there aren't too many AV receivers on the market that can match it.

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The Good
  • The Onkyo TX-NR646 has a powerful, dynamic sound. Not to mention it's loaded with the latest and greatest features including HDCP 2.2, Dolby Atmos and DTS:X.
The Bad
  • The 646 could use a makeover. The interface and remote are both starting to look dated. Onkyo's decision to move the USB input to the back is inconvenient.
8.6Overall Score


Onkyo TX-NR646

Onkyo TX-NR646 Review

Appearance & Design

Onkyo TX-NR646 RemoteOnkyo’s AV receivers are probably over due for a design overhaul. Their receivers have all sported the same look for the past few years. It’s almost like going to the Detroit auto show every year and seeing the car manufacturers drag out the same old body styles year after year. If there is a glimmer of hope it lies in their new Z-series which brandishes a new look. However, the TX-NR646 like the rest of the receivers in the TX line uses the same design as past years, it’s big black and boxy.


The remote that comes packaged with the Onkyo TX-NR646 is passable, but it’s starting to show its age as is the on-screen interface. The overall layout of the remote is pretty good, but it’s loaded with buttons and until you get used to the layout you’ll spend some time searching for the proper selection. The on-screen menus are your basic black and white text interface. When you compare it to the GUI on Sony’s STR-DN860 and 1060, Onkyo’s comes up short. However, despite its short comings it’s easy to navigate and find what you’re looking for. It just needs a little pizzazz.


Onkyo also has a remote app for iOS and Android devices. The app has a pretty slick-looking interface and it allows you to control the basic functions of the receiver. Onkyo should just take the GUI interface from the app and adapt it for their receivers. If they did that, they would probably give Sony’s interface a run for its money.



Onkyo TX-NR646 Rear

Onkyo’s always been known for loading their receivers with tons of connectivity options, and the Onkyo TX-NR646 is no exception.  It comes packed with 8 HDMI inputs and 2 outputs. Three of the inputs are HDCP 2.2 compliant as are the two outputs. HDCP 2.2 is a copy protection standard that Hollywood’s adopting to deter people from illegally recording and/or copying their 4k Ultra-HD material. If your amp isn’t HDCP 2.2 compliant it won’t be able to passthrough any media that uses this encryption. There are some work-arounds for this inevitable problem, however the TX-NR646, since it is HDCP 2.2 compliant, won’t have any issues when 4K material is more abundant.


Besides the HDMI connectors, the Onkyo 646 also gives you 7 analog connections (including a phono input), a couple composites and three digital inputs. For multi-room arrangements the 646 also has powered zone 2 outputs and zone 2 line-outs. Oddly, Onkyo decided to move the USB input from the front of the receiver to the back. Which makes it extremely inconvenient to get to.



Bluetooth and WiFi are both built-in to the Onkyo 646. However, a surprise addition to Onkyo’s line-up this year is Apple’s AirPlay. Onkyo for some reason has resisted supporting AirPlay in the past, however it’s finally making its debut on Onkyo receivers this year.


Once you boot-up the Onkyo TX-NR646 you’ll find an impressive amount of music streaming services such as Spotify, Pandora, SiriusXM Internet Radio, Slacker and TuneIn. The 646 uses a high-grade AK4458 digital-to-analog converter (or DAC) to offer some of the best music playback that I’ve heard on an AV receiver at this price point. The Onkyo 646 also decodes an impressive number of high-res, lossless and compressed audio files including MP3, WMA, WMA Lossless, FLAC, ALAC, WAV, OggVorbis, AAC, Apple Lossless, and DSD 5.6 MHz.


While it’s laundry list of music formats is impressive, its list of home theater audio codecs are equally impressive. It decodes the normal hi-res formats such as Dolby TrueHD and DTS-HD Master Audio, but it also comes equipped with Dolby Atmos. The 646 also supports DTS:X however, it won’t be available until Onkyo issues a firmware update later this year. Both Atmos and DTS:X are object based sound formats that allow sound engineers to “place” sounds at specific locations in a listening area which creates a “3D” like experience.


Not many blu-ray’s support Atmos yet, but the list is growing. The more time I’ve spent with Atmos, the more impressed I’ve been so it seems if done right, Atmos really can deliver the goods.


Onkyo TX-NR646 Calibration & Performance

Onkyo dropped Audyssey calibration from its receivers last year and began using their own AccuEQ system. Onkyo’s system takes less time than Audyssey and I’ve found its measurements to be just as accurate.


With AccuEQ, you only need to take measurements from one location in your listening environment and the entire process only takes 1-2 minutes. After my system was calibrated I did go in and bump up my center channel level a couple notches and knocked down the sub a bit, but other than that it did a good job with my speaker distances, crossovers etc.

Streaming Functions

Streaming music via WiFi and bluetooth is a simple painless process. In wireless use I did not experience any drop-outs or disconnection. This may partly be due to the Onkyo TX-NR646’s dual WiFi antennas on the back. The sound difference between bluetooth and AirPlay is like night and day. Music sounded more dynamic and had more depth via AirPlay. If you have an Apple device you’re better off using AirPlay instead of bluetooth for streaming music.


Sound Performance

This first thing I noticed right off the bat was that the Onkyo TX-NR646 has no shortage of power. Rated at 170 watts of juice, it’s capable of getting loud….very loud. I only began hearing the slightest amount of distortion when I cranked it to near max levels.


Listening to music on the Onkyo I have to wonder if Beats by Dre had a hand in the design of the 646. When listening to music the Onkyo produces a true-to life experience and sounded especially fantastic with hi-res music files. For compressed MP3’s, the Onkyo 646 has a built-in music optimizer which is designed to enhance compressed audio. While the treble and mid-range did sound fuller, the bass response was off the charts. I’m an admitted bassaholic so the music optimizer really amped up the bass response especially with pop and Hip-Hop tracks. However, I found that for Classical, Jazz and Rock, the music optimizer seemed a little heavy-handed so I preferred to listen without.


The Onkyo really shines in the movie department. In one scene in Edge of Tomorrow, military drop ships are taking off from their military base, the sound of the ships sweeps from the front of the room to the back. The transition from my front speakers to the surrounds was as seamless as I’ve experienced with any AV receiver. In fact, I had to replay this scene 3 times just to make sure my ears weren’t playing tricks on me.


Switching over to the Amazing Spider-man 2 and the Expendables on blu-ray both solidified my belief that the 646 is a great movie performer. In Spider-man 2 , Electro’s lightning bolt buzzed around the room electrifying my entire listening area. With Expendables, bullets seemed to wizz and zing past my head putting my right in the middle of the action.
Jupiter Ascending Blu-RayI happened to have the 646 in our office at the same time that I had the Denon AVR-X2200W so I was able to do a side by side Dolby Atmos comparison. Jupiter Ascending, which is one of the latest movies to feature Atmos encoding, was a good test for both.  With Atmos enabled speakers my listening area definitely felt more alive as explosions manifested themselves overhead and spaceships zoomed by. With prior movies, Atmos seemed to be a tacked on feature, but with Jupiter it seemed that the sound mixers were deliberate in their intent to fully utilize the new format. When comparing the Denon X2200W to the 646, the 646 managed to barely edge out the 2200W as it provided a smoother transition between my front, elevation Atmos modules and surround speakers.



Onkyo almost hit it out of the park with this one. The Onkyo TX-NR646 sounds fantastic for movies and great for music. With bluetooth, WiFi, AirPlay, Dolby Atmos and DTS:X support the 646 is a fantastic value. If Onkyo had just overhauled the user interface, the remote and kept the USB input on the front,  I could have given this 5 stars.

Where to Buy:

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