Review: Cambridge Audio 640a Integrated Amplifier

Category: Amplifiers

The Cambridge Audio 640a Integrated Amplifier:

"You get what you pay for." We've all heard that from some glinting-white salesman's mouth at one point in our lives or another. It seems to be the law of the land when it comes to HiFi, too. Few, including myself, will argue that money doesn't buy great sound.

Who I am, and why my opinion is of any merit, whatsoever.
Having been raised in the car-audio era (I began driving right around the point of Soundstream and Rockford Fosgate's arrival on the scene as key car audio players), I am a solid state fan, for sure. Now, let's not confuse my brand of audio with those misfits we loathe, cruising by our houses at three in the morn, P-Diddy broadcasting via a ski-slope-shaped eq curve and twelve 18" subwoofers. No, I am from the sound quality school of car audio, and that carried-over to my tastes in home audio, too.

Much of my adolescence, and a good part of my twenties, was spent winging through car audio products left and right, in a search for that ever-elusive "nirvana" we audiophiles all crave. It led to competition, where, for my limited budget, I faired quite well, being invited to the 1995 USAC World finals in Houston, TX. (I was outgunned at the finals, my $3500 stereo playing against factory-prepped cars built with backing from ALPINE, Clarion, and Rockford, etc. But, to this day, I feel that my sound quality, and mastery of system parameters (perfect scores on SQ, noise floor, and RTA curves in several key contests nationwide) led me to where I am today as a HOME audiophile--constantly in search of that extra bit of purity from my systems.

That said, I am always listening TO the MUSIC, and rarely to the song, if you catch my drift. Very scarcely have I been impressed enough with my stereo setup to simply relax and enjoy myself without wodering if a cable here, or a few more degrees of toe-in there could improve what I'm hearing.

Ummm...The Review, Please?

In comes the Cambridge Audio Azur 640a. One of my Conrad Johnson amplifiers was in for upgrades, as many of my components end-up, awaiting new caps, etc., in hopes to improve what most would consider wonderful sound already. I decided to hook an integrated amp into my system, circumventing seperates for a change (as best I could, though I MUST use an outboard DAC, period). I looked around on the net, and read a few reviews on the Creek, a few on the Copland, and a few on the Cambridge Azur 640a (I was sceptical of some of these reviews. What HiFi? stated that the 640 was class A, and for $500 USD, I doubted this could be the case.) Nevertheless, I ordered the unit from Audio Advisor, and it arrived a few days later via FedEx (free shiping, too).

The Packaging
My first impressions of the Cambridge were "Wow! This thing is really packaged well!" and "Ooh, the remote has an aluminum faceplate!" Both the remote, and the unit were packaged in their own blue nylon bags for protection. I rarely see this good a packing job from other companies (though Conrad Johnson, boxes their stuff in bomb-proof boxes you have to see to believe). Cambridge's owner's manual is a bit lacking, and could really stand a revamp, as it is designed to cover both the 640a and 540a in one booklet.

Build Quality
Cambridge touts this unit as having a "damped, vibration resistant cabinet." While its shape is unique, and may help damp some airborne vibrations, I still felt it was lightweight enough to merit a sandbag on top of the chassis.
The unit's fit and finish was a 9 out of 10. The front of mine (I opted for the black unit, but silver is available, too) was lit with interesting, intense blue leds. One denotes power/stdby, and the other, which source is selected. There is also a blue LED which blinks if MUTE is selected. Speaking of which, mute is auto-selected when powering the unit up, until the initial "thump" has supressed. (This seems to work, since the unit has NO turn on thump whatsoever.) The remote is pleasant, but a bit too large, and the batteries included with it were all but d.o.a. The volume pot is a bit dissapointing, and seems jumpy when used with the remote control(guys, I'll say this once-Gimme a damn volume pot that's worth a darn, and SKIP the remote. Screw mass marketing). When listening at low volumes, you must tap the volume button a few times to get it going, then HELLO, the amp opens-up loud and clear. There is no happy medium, unless you tweak the knob on the unit by hand (so, true audiophiles will find the remote USELESS, except for the MUTE function and source select). Speaker binding posts were a bit plasticy--not crappy, just plasticy. They did, however, hold the wires tightly and securely. Other than these two flaws, I had no major concerns about the 640a's build quality; it felt as nice as many amps I've demo'd in the $800-1000 range. Touch controls feel snappy, but not hard, and the volume knob is liveable. I also like the tone control bypass; this is evidence that Cambridge gives a hoot about sound, and that's good news, indeed.


Upon hooking the 640a to my rig, I turned it on, and played a few burn-in tracks at low volumes over the next 72 hours (there is actually a factory-placed sticker advising owners to allow for burn-in, more evidence that Cambridge is serious about HiFi). After a few days' burn-in, the unit was ready for my scrutiny. However, I was not ready for what I was about to hear!

Bela Fleck and the Flecktones' "Flight of the Cosmic Hippo," which is a MUST if you dig dynamics, strings, and just plain craziness, was the first of many discs I auditioned on the Cambridge. I was immediately pulled-in to the soundstage. It was fairly wide, as wide as it is through my Conrad Johnson setup, but it was also TALL and well-layered. When I say tall, I mean, Fleck's banjo seemed to hover above the speakers, while Vic Wooten's bass licks were well-grounded, and had a definitive space about them. This CD contains lots of intermingling information, cymbals, strings, even harmonica sounds, which can be muffled, or even confused for each other on poor systems. I was amazed at the ease with which I could pick specific instruments and their respective beats out from one another.
"Mighty impressive, indeed." I thought aloud. For its modest price, I was instantly impressed with how well the 640a handled such a demanding CD.

Treble was right as it should be, not bright, but shiny where it sould be. Midrange on this unit is amazing for what I paid. Guitar strings, plucked or strummed, retained much of the clarity and realism I am accustomed to from units three or four times the Cambrige's price. On "Use Me," Mick Jagger's voice is completely correct, and the Cambridge reveals his true attitude throughout the song. Lenny Kravitz sings with Mick on this song, and his voice is equally well defined. Bela Fleck's Harmonica and Piano sounds each held their own, as well.

My only gripe with sound was the seemingly "loosish" bass. The amp packed alot of uuumph for its modest power rating, but the low-end was a tad fatter than I like. (This has toned-down alot now that the unit has been broken in for a month or so.) I surmise that most consumers enjoy this type of low end, not that it is "boomy," far from it. It just seems a bit more "there" than it should be by about 3dB or so. As stated above, much of this low end "thickness" has calmed itself with time. Male voices, especially deep ones, like the background voacls on "Diamonds on the soles of her shoes" by Paul Simon, sounded true, and were niether muffled, or overbearing. The vocalists' nasal "Ooooummph Ooooumph" sounds were handled beautifully, with even the soft sounds of their exhalations carried out to completion. Very, very nice.

The depth of the image was great, with distant vocals on "The Ultimate Test CD" and "My Disc" sounding as close to perfect as I have heard from any integrated unit under a grand. (Now, on the depth track of "The Ultimate Test CD," I did note an odd tendency for the far-away voices to lose their authenticity in terms of ambient reflections.) This was the ONLY place where I could point to the speakers and say, "The esses are originating there." This really had no bearing on the image with actual music, however, and on Paul Simon's "Train in the Distance," the background seemed to almost extend beyond the rear wall by twenty or thirty feet! I attribute this to the Cambridge's complete lack of noise. There's NO noise. ZERO noise. Nada. With my CD paused, I could literally turn the volume WIDE OPEN, and there was zero hiss, crosstalk, etc., even with two sources running (I.E., CD and DVD playing, but only CD selected).

There is a "sweet spot" volume wise, where the 640a sounds its best, but this is typical of alot of components I have used over the ages. At moderate volumes, the presence is good, but go a few notches past and it becomes wonderful. This amp is snappy, rythmic, and quite dynamic, despite its modest price. In fact, I can point a few things out that this unit does better than the Conrad J. For one, it kicks the CJ's butt in terms of noise. There's zero hum, static, etc. at any listening level. Second, hidden, or micro details shine through with ease, if not better than the CJ, at least as well. Third, I do not miss the tone controls when switched-off. My CJ preamp lacks them all together, and some days I curse this. Not so on the Cambridge. It seems to portray the recording "as-is," and lets you just listen. Is that not "High End?" I say yeah.

Overall Impression

All-in-all, the Cambridge Audio Azur 640a is a complete bargain. Having also heard the Creek, which is itself a great unit, I can not justify spending the extra $300 (400 if you want a remote) simply because it is a Creek. The Cambridge holds its own against integrateds I've come across costing well over three times the 640a's $499.00 MSRP. Aside from a rather touchy volume pot, and a remote which could have been omitted in favor of replacing the pot with an Alps, or similar volume knob, I have no real gripes with the 640a. In fact, I am still amazed at the value which it presents.

I had initially bought the 640a as a temporary replacement while tweaking my other components, but this baby is a keeper! I can not think of an audio product that I've used in the last decade which holds a candle to the overall value and sound quality the Cambridge unit presents. It is laden with features, and looks as if it belongs on a rack with other, much more expensive components! For what I paid, I am amazed that I can sit back and enjoy the SONGS with this amp, and not think twice about twaeking a thing. In fact, I think the only people who will not like the 640a are the folks who produce overpriced equipment which barely exceeds the Cambrige's fidelity, if at all.

Top notch!

Supreme sound-per-buck value.
Contemporary looks of unit and remote.
Zero noise-dead silence even cranked wide open.

Shoddy volume knob gets a bit touchy.
Giant remote control could be left off for better volume knob.

Scale of 1 to 10:
SOUND: 8.5
BUILD: 7.5
Overall: 9! WOW!


Associated gear
Rotel RDC 980 Transport.

Rotel RDP 980 DAC.

$79.00 Panasonic DVD 31 DVD Player.

Pinnacle 1200C Tower Speakers

Hand-Made Digital Coax (75 ohm),
consisting of Quad-Field random geometry (6", and 1m, home brews, I'll be offering them soon on Audiogon).

Monster Cable THX Toslink.

Monster Cable 1000 Interconnect (1m).

Monster Cable Speaker Wire (soon to be swapped for my own design-more later).

Sand bag (placed atop preamp).

Custom floor spikes (pinnacle's, but modded with longer shaft to increase coupling.

Autosound 2000 "My Disc" Test CD.

The Absolute Sound's "Ultimate Test CD."

Bela Fleck "Perpetual Motion" CD.

Bela Fleck "Flight of the Cosmic Hippo" CD.

Mick Jagger "Wandering Spirit" CD (Hard to get right on many systems).

Paul Simon's "Negotiations and Love Songs" CD.

Similar products
Creek integrated.
Thanks for the review. I'm looking at integrateds in this price range too and have been wondering how the Cambridge compares with NAD. When I called a local NAD dealer with some questions about NAD, they told me about the new Cambridges and suggested they compare quite favorably to NAD. Anyone have any direct experience with the two?
I could never knock NAD, but...I have never been so impressed buy an NAD product as I was this Cambridge! It will always have a home, even if I use it for the DVD system! It is wonderful. NAD, Creek, and Cayin also make great bang-for-the-buck stuff, but the Cambridge (aside from the volume knob) is BAM! for the buck.

Great review! I was thinking of buying one of these but held off in part due to concerns about the remote volume control -- I need to be able to make fine adjustments. My other issue was that nobody has yet reviewed the optional phono stage. If anybody has a 540a or 640a with the MM board, please post a follow-up.
I also own one of these, and couldn't happier. Excellent all around, modestly priced IA. I found it to be very similar in performance and tonality to NAD gear.
I just got one too, paired up with the 640CS v2 cd player. SWEET!
This amp is great for the money spent.It sounds clean,extended,even a bit warm if paired with right gear.I have one for 2 years now.It was tested in few systems,including with Silverline Sinfonia speakers (20 000 $).
I am more than satisfied with it.
Strengths - Bass,treble,clean sound.LISTENABLE.
Weaknesses - Vocals sound a bit cold.This is noticeable if A/B tested against,for example,SET amp.It is not an issue in normal listening.
Overall, better than i hoped for.
I installed a v1 with a Cambridge 640C disc player at my next door neighbor's house 3 years ago, and I concur that this unit is astoundingly transparent and detailed, yet cohesive and musical.

In both my neighbor's and my system, we're driving a pair of 1st-gen Mirages and the matching small powered Mirage subs. My electronics up to now, however, are a Cambridge 640p phono stage feeding an Outlaw 950 functioning purely as a 2-channel analog line stage, feeding a 70wpc Amber Series 70 power amp.

Now I'm upgrading my speakers to new 3rd-gen Mirage OMD-15 floorstanders with the Omniguide waveguide. These speakers are biampable/biwirable, and can probably soak up a lot more power than the Omnisats I'm migrating from. If my 12-yr-old Mirage M5si's are any indication, the OMD-15s will come alive with biamping and lots of power.

I've been thinking of ways to biamp, and I think I'm going to migrate to a Cambridge 640A to function as both linestage preamp and tweeter amp. I'll use the Amber Series 70 power amp to push the woofers. I was thinking, at $599 (the price for v2), you'd be hard-pressed to find a line stage as fast and transparent as the 640A, yet the 640A also has a more-than-decent 75wpc power amp built-in as well. It should function quite nicely to power the tweeters.

Source is a turntable going to Cambridge's 640p phono stage. The $169 640p is so good for how cheap it is, it's practically a gift! Should be an ideal match feeding the 640A. After all, it was designed for it.
I recently tried a few of the Cambridge CD units, and was impressed with the cost/value. I sold the 640a, and regret ever having done so. It really was a relaxing preamp to listen to. A little Paul Simon "Graceland," and who needs a beer?