I started off my testing, as usual, with Spears & Munsil's High Definition Benchmark Blu-ray, not really expecting much, since Cambridge doesn't really trumpet the video processing capabilities of the Azur 751R. But it should, because in every test but one, the receiver equaled or exceeded the 1080p upscaling capabilities of my OPPO BDP-93, knocking practically every test (including the 2:2 deinterlacing test, which many receivers fail miserably) out of the water. Only a few weird artifacts in the white ring on the Jaggies test kept it from getting perfect marks, and it should be noted that those artifacts weren't in evidence on any actual real-world video material. So, for all practical purposes, the video processing of the 751R should be considered virtually flawless.
But trust me when I say that no one is going to buy this receiver for its video processing capabilities, despite its prowess in that regard. The audio is what matters here and, despite my grumblings about the setup woes involved with trying to use Audyssey 2EQ, once I settled down with some actual demo material, all was forgiven.
As I said in my review of the Denon AVR-X3000, there are two approaches to selecting demo material for reviews. Although I can see the value of using the latest releases, I prefer to take the more boring, redundant approach of sticking to the same handful of discs that I know well. So my apologies if you don't want to read about my impressions of Blue Man Group's Audio DVD-Audio disc (Virgin) again, but believe me when I say that I've never heard it sound like this through any receiver - not even the Anthem MRX 700. In fact, I'll no doubt draw my fair share of hostile comments for saying this, but the only system I've auditioned at home that renders tracks like "Rods and Cones" and "Mandelgroove" with as much dynamic range, detail and gusto of the sort delivered via the 751R is my Anthem D2v/A5 setup in the home theater.
Moving on to Fleetwood Mac's Rumours (WEA) on DVD-Audio, again, I found myself positively staggered not only by the oodles of dynamic range, but by the outright precision with which the receiver hangs distinct elements of the mix in the air. I'm really not sure whether to chalk this up to the Anagram Technologies ATF upsampling, the incredible power reserves of the unit (Cambridge is one of the few receiver manufacturers to rate power output with all channels driven, so that's certainly part of it), or some mix of both. But no matter: anyone who says that all receivers sound the same has never heard the Cambridge Audio Azur 751R. And anyone who has heard the 751R and still contends that all receivers sound the same is quite frankly deaf. I'm not saying it blows away this room's reference Anthem MRX 700; I'm merely saying that the receivers sound strikingly different, with the Anthem delivering - via the same speakers, mind you - a more "big theater" sound, whereas the Cambridge is more capable of aiming a stray guitar note at the third button from the top of your shirt and missing by no more than a half-inch.
Just for kicks, I decided to dig into the receiver's menus to engage both of the EQ curves available with 2EQ - Audyssey and Flat - and both absolutely laid waste to everything that is so wonderful about the 751R's sound. The front soundstage collapsed from a big bombastic bubble into a thin shell of its former self. The delicious midrange thinned to the point of snapping with both curves, and Flat introduced a brittle, sickly high end that sent me scrambling through the menus once again to turn it off. Anyone who spends the money on such an unabashedly high-performance receiver and engages either of the 2EQ curves should be forbidden by law from buying anything but Bose ever again.
In complete defiance of conventional AV receiver wisdom, the 751R also sounds incredible in stereo. In truth, its 170 watts of output in stereo mode turned out to be a little too powerful when trying to drive a pair of the Monitor Audio MASS satellites alone to appreciable volume. I temporarily borrowed a pair of Paradigm Studio 100s from the main theater so that I could crank the Man of Steel: Original Motion Picture Soundtrack (WaterTower Music) to the high heavens in two-channel mode for a bit. And crank it I did. I often find myself dialing back on the volume of most audio gear long before the point of pain, but the combination of the 751R and the Studio 100s turned out to be a dangerous mix, if only because the sound never really reached the sort of edgy, rough point that warns you you're pushing the system too hard.
This CD is also, by far, one of the most dynamic I've heard in ages, with whisper-quiet passages that quickly explode in a thunderous release of bass and a deep, rich soundstage that the 751R rendered beautifully, except when I tried Audyssey's 2EQ curves once again to gauge their effect on stereo material. Track 8, "Terraforming," devolved from a huffy, holographic audio wonderland to a flat mess, and 2EQ even seemed to sap some of its dynamics out of the mix. With the 2EQ curves turned back off, I honestly had to walk up to the front panel a couple of times just to convince myself that no Dolby Pro Logic II or DTS Neo:6 processing was engaged in the process. Thankfully, the lovely but simple remote does include direct access to all stereo and surround modes via separate buttons, although a word of warning is in order here. Press the Stereo Modes button once, and it puts the receiver in pure two-channel mode. You have to press it again to get to Stereo+Subwoofer, no matter how you have your crossovers set.
A similar issue occurs with the headphone amp. Plug in a set of phones, and the 751R automatically engages Dolby Headphone mode. Even though I've never particularly dug Dolby Headphone, I like the implementation here. It's subtle but effective. And you can press Stereo Modes with headphones plugged in to activate a pure two-channel, unprocessed signal. Do be careful if you press Surround Modes to engage Dolby Headphone processing again, though; press it too many times, and the receiver turns on DPLII or Neo:6 processing, with an incredible bass and gain boost that nearly wrecked my HiFiMan HE-400 cans.
Given the Cambridge Audio Azur 751R's incredible performance with music, it should go without saying that movie performance is tippity-topnotch, too. Sometimes things just need to be said, though, so I popped in The Incredible Hulk (Universal) on Blu-ray and skipped to Chapter 5, in which Ed Norton goes all Hulk Smash for the first time. Again, dynamics were incredible, tonal balance was exquisite, and imaging was spot-on. I should say, to be fair, movies demonstrate the one single solitary advantage of having Audyssey 2EQ onboard, and that's Dynamic EQ and Dynamic Volume. (Okay, perhaps that's two advantages, but I wasn't expecting the Spanish Inquisition.) If you tend to watch a lot of television in the home theater or media room, or you like to watch action-packed movies late at night without sacrificing surround sound, Dynamic Volume's three settings work quite well, and Dynamic EQ keeps things tonally rich at practically any listening level.
It may sound like I've been a little hard on the Cambridge Audio Azur 751R receiver regarding Audyssey 2EQ, but the fact of the matter is that, at this price, Cambridge should either eat the extra cost of stepping up to the vastly superior Audyssey MultEQ XT32 or be brave enough to say poo-poo to room correction entirely. 2EQ is, by any measure, worthless and wouldn't even be worth mentioning, except for the fact that it figuratively does more harm than good. Thank goodness you can turn off the 2EQ curves, and that's why I can't hold its inclusion against Cambridge too much. If there's a real black mark against the 751R, it's that there isn't a manual EQ onboard to effectively deal with bass nodes, which means that, as I said, you're either going to spend a lot of time fussing with the position of your subwoofer, or you'll have to buy one with built-in room correction.
As I ran into with the Monitor Audio MASS system, the receiver is also quite frankly almost too powerful for most small satellite speaker systems.
My only other legitimate beef is that the included main zone remote (wholly separate from the packed-in Zone 2 remote), while gorgeous and well-built, not only squeaks like one of my pit bull's chew toys when you press the navigation button, but it also lacks any learning or universal remote capabilities. And it isn't backlit. Granted, if you're in the market for a receiver at this price, chances are good that you're bringing your own control solution to the credenza, but I'd love to see Cambridge Audio include a remote control more in line with the more fully-featured one included with its Azur 752BD universal player (stay tuned for that review).
Comparison and Competition
At $2,999 MSRP, the Azur 751R doesn't have a lot of competition in the standard big-box retail receiver arena. The $3,100 Pioneer Elite SC-79 comes to mind, and it does include a number of features that the 751R lacks, like AirPlay, network audio steaming, THX certification, and 4K video capabilities. However, it boasts nowhere near the power with all channels driven, and, to be honest, I haven't heard it. So there's that.
Anthem's $2,000 MRX 700 is probably a better comparison, given its equally good - although very different - audio capabilities, but of course it lacks the 751R's massive power capabilities, as well as its 7.1-channel analog inputs. It does, on the other hand, sport what I consider to be the best room correction on the market.
In truth, though, I think the 751R's stiffest competition is probably Cambridge's own 651R. The two models are so similar that they share the same instruction manual. The 651R merely lacks one HDMI input, the amazing USB DAC capabilities of its big brother, and 20 to 30 watts of power, depending on whether you're driving two channels or seven. Yet it costs, on average, about $700 less.
For more comparisons, please visit Home Theater Review's AV Receiver page.
The Cambridge Audio Azur 751R delivers the sort of incredibly impactful, dynamic, richly textured and oh-so-detailed audio you would expect from really good separates, and its stereo performance, with speakers that can handle its power, is quite frankly mind-blowing. I'm not hanging the "for a receiver" caveat on that. It's just damned good.
If you're in the market for a truly amazing-sounding receiver and don't need built-in streaming features - or network connectivity of any sort, for that matter - and don't mind the lack of any useful room correction, you simply must audition this receiver. I'm not saying it's perfect, I'm merely saying that there just isn't much else on the market like it.