Cambridge CXA81 MKII Amplifier Review

[amirm]

This is a review and detailed measurements of the Cambridge CXA81 MKII integrated stereo amplifier with digital inputs (USB, Toslink, Coax) and Bluetooth. It was kindly drop shipped by a member and costs US $1,199.

There are no visible changes from the original CXA81 I tested. I *think* the same is true of rear panel features:

I am still not a fan of the overloaded input button that toggles between BT and USB depending on how many times you press it. Otherwise there is not a whole lot to complain about. Let's see how it measures relative to original.

Cambridge CXA81 MKII DAC Measurements
Inclusion of Pre-out enables us to test the performance of internal DAC so let's start with that dashboard with volume adjusted to deliver nominal 2 volts:

As with the original version, the output starts to saturate at 2 volts with substantial increase in distortion. Lowering the output to 1.6v or less remedies that:

I was hoping this would be fixed in this revision but is obviously not. Peak SINAD of 103 dB falls in competent category but that needs to be there with 2 volt output, not 1.6. We see the same saturation in IMD test:

Going with 1.6 volt output, dynamic range is very good for class:

Linearity shows incursion of noise at lowest levels:

There is a lot of low level jitter/noise components (more with grounded USB input):

There is also a pronounced 4 kHz jitter component as evidenced by those two spikes at 8/16 kHz.

Filter response is better than average:

Frequency response is good but I was surprised by the much higher output level from sub out:

As documented and seen above, the main pre-out is not filtered. And sub out is quite extended so you need to use the filter in the subwoofer.

Multitone performance is good:

We see the saturation issue again in wideband THD sweep:

But even without that (green curve), performance needs to be better than our reference ($99 DAC that came out years ago).

Cambridge CXA81 MKII Amplifier Measurement
Starting with analog input and setting gain to 25 dB we get good performance:

As our ranking shows:

Crosstalk/channel separation is very good:

As is frequency response:

Multitone output is disturbed by power supply spikes and increased distortion at higher frequencies:

Power output more or less meets spec:

Protection circuit is quite forgiving allowing me to push the amplifier at all frequencies to well past clipping:

I was impressed by the ability to produce the same power even at 20 Hz -- where a lot of amplifiers pull back.

The top is quite far from heat generating components so you don't directly feel how hot the amplifier runs. So let's use our thermal camera to look inside:

There is a toroidal transformer in the middle and amplifier circuits surround it. As I showed in the dashboard, idle power consumption is 49 watts.

There is too much of a spike on both power on and off for my liking:

Overall, this is a competent amplifier.

Conclusions
The story here is one that we can predict across many manufacturers: quite average DAC performance with competent amplifier implement. Here we are at revision 2 and I am disappointed that the company despite reviewing the original testing with me, has made no improvements in any area that I can see, including limitations such as 1.6 volt output. And a somewhat confusing user interface.

Personally I can't recommend the Cambridge CXA81 MKII. You can do better with a stand-alone DAC and amplifier, albeit losing the preamplifier feature in most cases.
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As always, questions, comments, recommendations, etc. are welcome.

Any donations are much appreciated using: https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/

 

[amirm]

Reserved for @AdamG to kindly post the specs.

Manufacturer Specifications:

 

[_thelaughingman]

For $1100 dollars, its a jumble of mess that has no value.

 

[Timmy]

A refurbished unit was kindly drop shipped by a member.

Not sure about the market volume of refurbished units in this price range. Nevertheless, I won’t buy one. So any measurements with refurbished stuff have only very limited value in my point of view.

 

[sam_adams]

So let's use our thermal camera to look inside:

It's almost as hot as Phoenix inside there!

 

[Sylvia]

Thanks for this review! Great job!

 

[Ajax]

Another example of a highly regarded English brand under performing. Can't help but feeling duped over many years by the HiFi magazines, who were glowing in their admiration for these brands.

For the same money you can have a minidsp Flex or WiiM front end, combined with a hypex power amp assembled by one of several competent manufacturers.

It must now be clear to even the most ardent "subjective" that the only way you can be assured of getting transparent and high performing gear is by measuring it. No ifs or buts.

Your work is invaluable Amir, thank you.

Edit: typo

 

[calugg]

*SIGH!* This is just really disappointing. Too hot, too heavy. Too pricey for the performance.

 

[posvibes]

I don't quite understand why the company insists on going down this road when there are newer tried and truer technologies now in the market and have been for sometime.

The King Canute Complex at play?

 

[phoenixdogfan]

Great review, Amir. I feel exactly as you do: Given there are so many excellent amps and dacs out there, it seems there really is no need to pay over $1,000 for this level of mediocre and quite frankly antiquated performance. Just go buy a pair of Fosi V3 Monos or a Topping PA 7 Plus, and any decent DAC, or, if you need the DSP features, a miniDSP Flex. More power, features and performance at a lower price just by getting those kind of separates instead.

 

[mike435]

Thank you for this review Amir! Excellent work and valuable data as always!

 

[diddley]

Thank you Amir for a highly anticipated review. to bad the outcome is mediocre.
But I am still happy with version one except for the fact you can get past 0100 then it really starts to distort.

 

[amirm]

Owner just told me it is not refurbished and was purchased from company direct. I corrected the review.

 

[AdamG]

Hi Amir. Thanks for the review. Loving the new “Heat Map” data. Noted a 55.8 degree Fahrenheit temperature increase. That’s a pretty large heat load for 2 channel amp. Love the expansion of more data points.

 

[vkvedam]

That was expected, thanks @amirm.
I'll eat my hat if any of the mainstream Class AB design cross the -100dB barrier. What Benchmark did is/was remarkable.

 

[restorer-john]

That’s a pretty large heat load for 2 channel amp.

That temperature is honestly nothing for an amplifier or an amplifier of that design. It has proper heatsinks, sensibly designed and good ventilation.

The problems occur when you have 60-100 degrees C on internal components, no heatsinking, no airflow etc.

Here's a Cambridge Azur 840A (much more powerful) gathering dust at my place. Same central design- huge heatsinks, plenty of devices, and honestly pretty well made. Sadly, they cheapened out with dubious capacitors and "Massuse" brand relays so this one is destined for the spare parts bin.

 

[GD Fan]

It isn't clear what the value proposition is here vs. many similarly priced AVRs which bring far more to the table.

 

[pablolie]

I honestly don't see the value in measuring the DAC portion in an integrated Amp with the same expectations as the stand alone ones. no one in their right mind would buy an integrated Amp to use it as a DAC, prolly means you're not using 80 per cent of the features you pay for, plus you know the DAC design is matched to the Amp that is included. It's a bit like expecting active speakers to have an Amp output so you can use them to drive other speakers. bit silly to me.

 

[restorer-john]

I honestly don't see the value in measuring the DAC portion in an integrated Amp with the same expectations as the stand alone ones.

You want to know where the performance bottleneck is. And most people who buy a product like this are more likely in my opinion to use the onboard D/A than be buying another external DAC-in-a-box.

Testing through the preamp is the only option as Cambridge hasn't fitted a tape out.

 

[milosz]

Good heatsinks. Otherwise, well, you COULD listen to music with it. Not as much output power as I'd like to see for the money. Good to see solid amp performance all the way down to 20 Hz, speaks of a good stiff power supply.

The DAC doesn't measure very well. STILL, I'd like to see double-blind tests proving that this matters. I'd like to see scientific proof that listeners can hear the difference between this DAC vs something from, say, Topping. We can MEASURE a difference, but does that measurement translate to an audible difference- or are we just counting how many audiophiles can dance on the head of a $400 RCA plug? I don't know the answer. I WANT to know!