Let's just go ahead and get his out of the way right from the giddy-up: 8K 8K 8K 8K 8K 8K 8K! It's the catchphrase of the consumer electronics word right now (well, it's at least tied with "Coronavirus"), and it's going to be appearing on everything from TVs to video game consoles to AV receivers more and more frequently as the calendar turns to 2021. The Denon AVR-X6700H ($2,499 at Crutchfield and Amazon) is the first of a new batch of 8K-capable receivers to cross our threshold for review, which makes it pretty exciting... but maybe not for the reasons you expect. And almost certainly not because it supports 8K video passthrough and upscaling.
The thing is, I don't have an 8K TV yet, and chances are very good that neither do you. I also don't have any 8K-capable source devices and likely won't until I get my front paws on the PlayStation 5. But as I said in my recent primer on HDMI 2.1, 8K resolution isn't really the draw here. The far bigger deal are other new features of the HDMI 2.1 specification, including support for higher refresh rates, Variable Refresh Rate (VRR), Quick Frame Transport (QFT), and Quick Media Switching (QMS).
And the Denon AVR-X6700H supports those, along with resolutions up to 8K60AB (meaning 8K@60Hz, both compressed and uncompressed), although only on one 40Gbps input (specifically HDMI 7, which is also the only input that can handle an incoming 4K120 signal). The other six rear-panel HDMI inputs are 18Gbps, and only support up to 4K60, but all do support HDCP 2.3 copy protection, along with VRR, QMS, and ALLM (Auto Low-Latency Mode). HDR10, HDR10+, Dolby Vision, and HLG high dynamic range formats are also supported on all HDMI inputs.
Any of the video inputs (including component and composite) can also be upsampled to 8K if you have a compatible display. And there's also a front-panel HDMI port, but its input is limited to YCbCr 4:2:0.
HDMI output comes in the form of 8K-capable Monitor 1 and Monitor 2 outputs (the former with eARC support), along with a 4K-capable Zone-2 out.
As its full name indicates, the AVR-X6700H 11.2 Ch. 8K AV Receiver features 11 amplified channels (with output rated at 140 watts per channel into 8 ohms, full bandwidth, two channels driven) and dual subwoofer outputs that can be measured, delayed, and leveled independently. Room correction comes in the form of Audyssey MultEQ XT32, and the X6700H supports the MultEQ Editor app for more advanced setup. The receiver also boasts 13.2 channels of processing, so you can add an external two-channel amp (or a full thirteen channels of amplification) to expand its output up to 7.2.6 or 9.2.4 channels. In addition to Dolby Atmos and DTS:X, the X6700H also features Auro-3D and IMAX Enhanced, and will eventually add DTS:X Pro processing via a future firmware update.
Another big new feature this year -- one that we'll dig into in a bit -- is the addition of two different speaker presets, which can be recalled at the press of a button.
In addition to the HDMI ports and preamp outs detailed above, the X6700H features dual coaxial and optical digital inputs, along with a wealth of analog connectivity. It also has two component video inputs (and one output) and four composite video inputs (and two outputs), along with six stereo analog inputs and one phono in (all RCA), Zone 2 and Zone 3 stereo analog outputs (RCA), FM and AM antenna connections, and your choice of control connections, including RS-232, Ethernet, 3.5mm IR input and output, and dual 3.5mm 12-volt triggers.
The X6700H features super-high-quality five-way binding posts for its speaker-level outputs, arranged (mostly) horizontally along the bottom of the chassis. There's not quite room for all 13 pairs, so two of them are stacked on the right side. And just to reiterate, you can't use all 13 pairs of binding posts concurrently, since the receiver only features 11 channels of amplification. The front left & right, center, and surround left & right outputs are fixed; the remainder (surround back left & right, height 1 left & right, height 2 left & right, and height 3/front wide left & right) are assignable.
First-time setup is handled by the same excellent wizard we've seen on Denon products for years now, although I mostly skipped it in favor of manual setup. As I generally do, I opted to use the MultEQ Editor app instead of the Audyssey setup built into the receiver's onscreen display and, as usual, I set a max filter frequency of 600Hz for all channels to tame standing waves and other issues related to room resonance without affecting imaging and overall tonal balance. For more info on this, you can see my most recent primer on room correction, which is in dire need of an update but still suffices if you want to understand the principles.
For some reason, the MultEQ Editor app didn't do its usual admirable job of dialing in the levels and crossovers for my RSL CG3 5.2 speaker system (reviewed here). I generally use a 110 Hz crossover for the bookshelves and a 90 Hz crossover for the center, but Audyssey decided that a 90 Hz crossover was appropriate for the front left and right bookshelves with a 60 Hz crossover point for the surrounds and center speaker. No idea what's going on there. I ran the setup twice just to make sure the error wasn't mine, but the results were the same. Both times it also set the levels for my subwoofers about 13dB too low.
Those were all easy fixes, though, and when I temporarily added a quartet of GoldenEar SuperSat 3 speakers, hung from the ceiling to serve as height channels, it handled the crossovers and levels for those quite well.
As mentioned above, Denon has added a new feature called Speaker Presets, which work similarly to the Speaker Profiles found on Anthem's MRX receivers. The possibilities here are nearly limitless, but just to give you an idea of a few things you could do with Presets: You might decide to have one preset where Audyssey is run with seven measurement positions over a large area for movie night with the fam and another that relies on just a few measurements in a tight configuration for when you're listening alone. Or you could have one setup for full Atmos and another for 5.1 or 7.1 with height speaker virtualization turned on. Or one for Atmos and another for Auro 3D. Or you might have one preset for daytime listening, with all of the receiver's dynamic range compression functionality turned off, and another for nighttime listening that includes Dynamic EQ and Dynamic Volume, as well as Low Frequency Containment, turned on.
Speaking just for myself here, after I finished pushing the receiver to its limits with a full Atmos speaker setup and reverted to my preferred 5.2-channel setup, I configured one preset with height speaker virtualization on and one with it off. If you're buying the X6700H for its power output and not its channel count, that might be something you also opt to do.
Switching between the two speaker presets does require digging around in the options menu of the receiver, but the four Quick Select buttons on the remote remember these speaker presets, as well as things like source selection, sound mode, etc. As such, you could set Quick Select 1 as your UHD Blu-ray player with Speaker Preset 1, for example, Quick Select 2 as your UHD Blu-ray player with Speaker Preset 2, Quick Select 3 as your Roku Ultra with Speaker Preset 1, and Quick Select 4 as your gaming console with Speaker Preset 2. The choice is yours.
Another new feature of the X6700H (at least to the best of my memory) is automatic input naming. The receiver recognized (almost) all of my devices and named them appropriately. The exception was my Oppo UDP-203, which it simply named "H," for whatever reason. Correcting that took mere seconds.
The X6700H is also supported by an excellent SDDP (Simple Device Discovery Protocol) driver for Control4 systems, so integrating the receiver into my home automation system was a snap. As soon as I fired up the Control4 Composer Pro software, the X6700H was sitting there in my discovered devices. All I had to do was drag the driver into the room in which the receiver was installed and bind my input and output connections. The driver gives you direct access to virtually every feature of the receiver, so I was also able to set a couple of custom buttons to switch between Speaker Preset 1 and 2, effectively aping the functionality of the Quick Select buttons found on the Denon remote.
As is usually the case, the AVR-X6700H features excellent video upscaling. I wasn't able to test its 8K upscaling prowess, and since I no longer have access to any analog video sources, I wasn't able to test its analog-to-HDMI upscaling, either. But 1080p-to-4K scaling was handled admirably.
I was also unable to test things like Variable Refresh Rate, but I did appreciate the X6700H's Quick Media Switching. Bouncing back and forth between my Oppo and Roku took roughly three seconds at most, compared with roughly six seconds on my Marantz AV8805 in the main media room.
For the first real test of the X6700H's audio capabilities, I popped in the UHD Blu-ray release of Baby Driver and let the first scene play. Simply put, the sound was ferocious, with the dynamic peaks of The Jon Spencer Blues Explosion's "Bellbottoms" erupting out into the room, and the screeching of tires, roaring of engines, and wailing of police sirens ripping through the soundfield like Hattori Hanzo steel through Aerogel.
The receiver easily drove the RSL CG3 speakers (86 dB sensitivity @ one watt/one meter) to peaks of 105dB in my 13-by-15-foot listening room without audible distortion. Though that's a skosh loud for my tastes, it's nice to have that kind of headroom.
With my go-to dialogue-intelligibility torture test, the Moria sequences from The Fellowship of the Ring: Extended Edition Blu-ray, I found the X6700H's performance unimpeachable, whether at THX reference levels or a few dB up and down from there. What's more, the receiver did a wonderful job of conveying the reverberant echoes of the underground, building the sense of space aurally with precision and clarity that I could find absolutely no fault with.
Switching to two-channel music, I queued up "Ventura Highway" by America from The Complete Warner Bros Collection 1971 - 1977 (Qobuz, 96/24), and found the X6700H's stereo performance to be excellent. The soundstage reached far beyond the constraints of speaker placement, imaging was precise, tonal balance was spot on, and the music exhibited oodles of detail. Would I have liked a little more soundstage depth? Perhaps. But the bassline still wove in and out of the sparkling acoustic guitars and vocals with a palpable sense of space. And I heard absolutely nothing in the way of audible distortion, aside from that baked into the music itself.
If you're curious about my constant references to "audible distortion" in the preceding section, this mostly stems from conversations with my fellow AV enthusiasts, many of whom have told me they're concerned about reports that Denon's new lineup of 8K-capable AV receivers reportedly have lower SINAD (signal-to-noise and distortion ratio) measurements as compared with last year's models. I did not notice any audible distortion in my review unit.
A bigger concern for me is that, as of this writing (August 19, 2020), the onscreen display of the X6700H is buggier than an Alabama backyard in August the last few nights before the mosquito-fogger truck rolls through the neighborhood. Just to give you a few examples of how these bugs manifest themselves: I prefer to set my volume readout to relative (-79.5 dB - 18.0 dB) instead of absolute (0 - 98). And when I set the AVR-X6700H as such, the front panel readout follows suit. But the onscreen display doesn't... at least not consistently. The weirdest damned thing is that it's dependent upon which input I have selected. If I'm on my Fire TV Stick, for example, the front-panel display will report relative volume while the onscreen display reports absolute volume. Switch to my Oppo, though, and I get both the volume popup and the info popup onscreen when I adjust the volume; The former reporting absolute levels and the latter reporting relative levels.
It gets worse. With the receiver set to the HEOS input, there are other major discrepancies between the OSD and the front-panel readout that actually interfere with the functionality of the receiver. Say you're rocking out to Pink Floyd's "Wish You Were Here" and decide that you'd like to hear it in surround instead of stereo. So you press the Music sound mode button on the remote, and a list of options pops up on the screen. You'd probably select "Dolby Audio - Dolby Surround" from the list, right?
The problem is, doing so actually puts the receiver into "DTS Neural: X" mode. And selecting "DTS Neural: X" puts it into DTS Virtual: X" mode. In other words, the selection on the OSD is always off by one, actually giving you the mode below the one you've selected. The receiver's front-panel display accurately reflects the sound mode you've selected but if your receiver is in a cabinet or another room, you'd be relying on an OSD that displays faulty information and effectively flying blind -- at least until a firmware update corrects the fault.
[[Editor's Note: A Denon representative told us their team has been unable to recreate this this problem on any of their in-house test units. Managing Editor Scott Wasser also has not encountered this problem on a Denon AVR-S960H he is currently reviewing, so it's very possible our X6700H problem is an aberration.]]
Consumers unfamiliar with Denon gear may also be surprised by how hot the unit runs. It definitely needs some breathing room, although the active and passive cooling never failed me even when I cranked the volume and left it there for far too long. I did notice, though, that the cooling fans were loud enough to hear even from across the room, so if you're watching a film with a dynamic mix of loud and quiet passages, you may pick up on that slight sonic intrusion when the action calms down.
Given that Sound United has beaten everyone else to the market with new 8K-capable AV receivers, there isn't a lot of competition out there for the AVR-X6700H at the moment.
Sister company Marantz has its SR8015 ($3,199), which is similarly spec'd in terms of output channels, processing, and amplification. The Marantz, of course, replies on that company's proprietary HDAM circuitry and will have a slightly different sound signature. It also features an extra component video input, as well as 7.1-channel analog audio inputs, which you may want to use if you have an audiophile multichannel disc player.
Sticking within the Denon line, stepping down to the AVR-X4700H ($1,699) from the X6700H will save you $800. The X4700H only has nine amplified output channels, though, and is limited to 11.2-channel processing. Its output is also a reported 125 watts per channel versus the X6700H's 140 (measured the same: into 8 ohms, full bandwidth, two channels driven). The X4700H also lacks the X6700H's Auro 3D center height channel assignability, won't be eligible for the DTS:X Pro upgrade, and is a little less flexible in terms of amp assignment overall.
It may have some weird quirks at the moment (although that could be an out-of-date observation by the time this review is published), but the Denon AVR-X6700H is still an impressive performer for the price. If you can live with some weirdness from the onscreen display and you're not overly concerned about all the brouhaha surrounding replacement capacitors (and I'm not here to tell you whether you should or shouldn't be), I don't think you'll regret buying it. That's especially true if you're planning to buy a PlayStation 5 or Xbox Series X at launch and want to make sure your AVR isn't the weak link in your AV chain.
Truth be told, though, for non-gamer AV enthusiasts, the biggest draw here is the Quick Media Switching. If I weren't a gamer and I needed an AV receiver in this performance class right now, I think I'd be shopping around for a closeout deal on 2018's AVR-X6500H. But who knows what lies just over the horizon? The wheels of AV innovation are spinning faster and faster these days, and the X6500H will be obsolete long before the X6700H is.
• Visit the Denon website for additional specs and information.
• Visit our AV Receivers category page to read reviews of similar products.
• Everything You Need to Know about HDMI 2.1 (Including Stuff You Might Not Ask) at HomeTheaterReview.com.