This is a review, listening test and detailed measurements of the CHORD Alto "Professional" hybrid power (speaker) and headphone amplifier. It was sent to me for testing by Bloom Audio and costs US $4,320.
CHORD's iconic design elements work quite well in this package, giving it an elegant while strong feeling. The volume control feels great especially with that dent in there for your finger. Four headphone outputs are provided but the balanced ones are just connectors and don't provide more power (see measurements below).
Then we get to the lightshow buttons which are as always, a step back from ease of use. It is so bad that the company provides a cheat sheet for you to use to decode which light means what. Fortunately they left light is dedicated to input and right one, to output so that part you don't have to guess. The center globe rotates and again thankfully, that doesn't do anything. You just push it in to power cycle the amplifier.
Sequential cycling worries me for a professional product. Imagine cycling to speaker output at high volume when you wanted headphone with the client present.
Back side shows the standard connections but with inclusion of recessed banana jacks for speaker output:
The speaker outputs had a tape over them and said to read the manual before using. I read the super brief manual but found no warnings about using them so don't know what that was about.
As you see, the power supply is a very high current 12 volt unit. It comes with super stiff AC cable and cable that connects to the amplifier. Fortunately the amp is heavy enough to not be tugged by it but still, it adds annoyance to having an external power supply to begin with.
Since this is a professional device, I limited my testing to using XLR input.
If you are not familiar with my amplifier measurements, please watch this tutorial:
[And subscribe to the channel
]
CHORD Alto Headphone Amplifier Measurements
As usual we start with our "unity gain" amplifier test where input and output voltages are the same:
I was disappointed by the spray of distortion products which likely indicates low amount of feedback. The spec is better than what I show but lacks detail to know if it is a comparable test. As is, performance is very much on the low side when it comes to noise+distortion:
As noted, I tested 4.4mm pentacon output as well and it is the same. Here is the noise performance:
Good with unity gain but residual noise is too high for any sensitive headphone or IEM:
Frequency response is nice and flat:
Now we get to good part: this HP amplifier produces a ton of power!
I have probably only tested one or two amplifiers with this level of output. Noise and distortion are compromised to get there but we get something useful for that.
Channel balance is excellent for an analog control:
CHORD Alto Power Amplifier Measurements
I set the output to speakers and volume to maximum:
We again get the spray of distortion. SINAD of 73 is some 7 dB worse than the average for all amplifiers tested.
Noise performance is excellent for a power amplifier (needed for the HP output to be any good):
Frequency response is load independent as one would expect:
Crosstalk is disappointedly high for class:
Distortion rises with frequency:
I think this is the worst 19+20 kHz intermodulation distortion results I have seen, since I started running this test:
Power output is modest but more or less matches the spec:
Once again noise and distortion are very high for the class.
At this point, I went into measuring power at 1% THD. For this test, I have to let the analyzer push the amplifier into clipping so it can then back down and find the 1% THD level. I typed in 4 volts for output. This immediately cause the ALTO to shutdown which is not unusual for some amplifiers. Alas, the amplifier would no longer output anything. Its front panel was working but no matter what I did, there was no output. I went back and tested the headphone output and it too was dead. I disconnected the power and cycled it a couple of times but it would still not work. I let it sit overnight and this afternoon, it started to work again:
I was too afraid to run reactive and regulated ("FTC like") tests as I wanted to listen to the unit. But did run the frequency power sweeps:
The increase in distortion is almost linear with frequency which indicates little to no feedback.
Soft power on/off produces strong pulses which are likely audible on speakers:
CHORD Alto Headphone Listening Tests
I connected my RME ADI-2 Pro interface's balanced output to the Alto and plugged in my everyday Dan Clark E3 headphone into it. The Alto drove the E3 harder than any amp I have used with it b before. Well before max volume, the loudness become intolerable while the sound remained clean without any distortion. Dynamics as you can imagine were superb with nothing to complain about.
I watched a video where it was said that the Alto was designed to drive multiple headphones. So while I had the E3 still plugged in, I also added the Audeze LCD-XC to another socket. The Alto drove both of them with ease and once again producing a level of power that was both pleasing and dangerous!
Conclusions
There have been amplifiers where company also recommends their use for headphones. But the Alto is the first one I have tested that claims that capability from start. Benefit of this approach is that there is the potential for tons more power which the Alto deliver son in spades. Both objectively and subjectively, you basically have unlimited amount of power to drive not one, but two or more headphones simultaneously. While you don't have independent control over each volume, I can imagine this being useful in a studio where the same headphone is used for multiple people to listen at once.
The compromises are kept low with distortion that is too high for my liking. Noise is good enough for most headphones but not IEMs.
I am not sure of the usefulness of driving speakers with it given the modest power output and potential issue with protection circuit. But I guess it comes for "free."
The cost is of course way up there. So you would have to value the looks, the brand, support, etc. and decide if it justifies its cost.
I am going to recommend the Chord Alto on the basis of its copious amount of power. Nothing ruins the performance of an amplifier more than when it runs out of juice.
My appreciation also goes to Bloom Audio for providing this sample for test.
EDIT: Video review posted:
------------
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/
CHORD's iconic design elements work quite well in this package, giving it an elegant while strong feeling. The volume control feels great especially with that dent in there for your finger. Four headphone outputs are provided but the balanced ones are just connectors and don't provide more power (see measurements below).
Then we get to the lightshow buttons which are as always, a step back from ease of use. It is so bad that the company provides a cheat sheet for you to use to decode which light means what. Fortunately they left light is dedicated to input and right one, to output so that part you don't have to guess. The center globe rotates and again thankfully, that doesn't do anything. You just push it in to power cycle the amplifier.
Sequential cycling worries me for a professional product. Imagine cycling to speaker output at high volume when you wanted headphone with the client present.
Back side shows the standard connections but with inclusion of recessed banana jacks for speaker output:
The speaker outputs had a tape over them and said to read the manual before using. I read the super brief manual but found no warnings about using them so don't know what that was about.
As you see, the power supply is a very high current 12 volt unit. It comes with super stiff AC cable and cable that connects to the amplifier. Fortunately the amp is heavy enough to not be tugged by it but still, it adds annoyance to having an external power supply to begin with.
Since this is a professional device, I limited my testing to using XLR input.
If you are not familiar with my amplifier measurements, please watch this tutorial:
[And subscribe to the channel
]CHORD Alto Headphone Amplifier Measurements
As usual we start with our "unity gain" amplifier test where input and output voltages are the same:
I was disappointed by the spray of distortion products which likely indicates low amount of feedback. The spec is better than what I show but lacks detail to know if it is a comparable test. As is, performance is very much on the low side when it comes to noise+distortion:
As noted, I tested 4.4mm pentacon output as well and it is the same. Here is the noise performance:
Good with unity gain but residual noise is too high for any sensitive headphone or IEM:
Frequency response is nice and flat:
Now we get to good part: this HP amplifier produces a ton of power!
I have probably only tested one or two amplifiers with this level of output. Noise and distortion are compromised to get there but we get something useful for that.
Channel balance is excellent for an analog control:
CHORD Alto Power Amplifier Measurements
I set the output to speakers and volume to maximum:
We again get the spray of distortion. SINAD of 73 is some 7 dB worse than the average for all amplifiers tested.
Noise performance is excellent for a power amplifier (needed for the HP output to be any good):
Frequency response is load independent as one would expect:
Crosstalk is disappointedly high for class:
Distortion rises with frequency:
I think this is the worst 19+20 kHz intermodulation distortion results I have seen, since I started running this test:
Power output is modest but more or less matches the spec:
Once again noise and distortion are very high for the class.
At this point, I went into measuring power at 1% THD. For this test, I have to let the analyzer push the amplifier into clipping so it can then back down and find the 1% THD level. I typed in 4 volts for output. This immediately cause the ALTO to shutdown which is not unusual for some amplifiers. Alas, the amplifier would no longer output anything. Its front panel was working but no matter what I did, there was no output. I went back and tested the headphone output and it too was dead. I disconnected the power and cycled it a couple of times but it would still not work. I let it sit overnight and this afternoon, it started to work again:
I was too afraid to run reactive and regulated ("FTC like") tests as I wanted to listen to the unit. But did run the frequency power sweeps:
The increase in distortion is almost linear with frequency which indicates little to no feedback.
Soft power on/off produces strong pulses which are likely audible on speakers:
CHORD Alto Headphone Listening Tests
I connected my RME ADI-2 Pro interface's balanced output to the Alto and plugged in my everyday Dan Clark E3 headphone into it. The Alto drove the E3 harder than any amp I have used with it b before. Well before max volume, the loudness become intolerable while the sound remained clean without any distortion. Dynamics as you can imagine were superb with nothing to complain about.
I watched a video where it was said that the Alto was designed to drive multiple headphones. So while I had the E3 still plugged in, I also added the Audeze LCD-XC to another socket. The Alto drove both of them with ease and once again producing a level of power that was both pleasing and dangerous!
Conclusions
There have been amplifiers where company also recommends their use for headphones. But the Alto is the first one I have tested that claims that capability from start. Benefit of this approach is that there is the potential for tons more power which the Alto deliver son in spades. Both objectively and subjectively, you basically have unlimited amount of power to drive not one, but two or more headphones simultaneously. While you don't have independent control over each volume, I can imagine this being useful in a studio where the same headphone is used for multiple people to listen at once.
The compromises are kept low with distortion that is too high for my liking. Noise is good enough for most headphones but not IEMs.
I am not sure of the usefulness of driving speakers with it given the modest power output and potential issue with protection circuit. But I guess it comes for "free."
The cost is of course way up there. So you would have to value the looks, the brand, support, etc. and decide if it justifies its cost.
I am going to recommend the Chord Alto on the basis of its copious amount of power. Nothing ruins the performance of an amplifier more than when it runs out of juice.
My appreciation also goes to Bloom Audio for providing this sample for test.
EDIT: Video review posted:
------------
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/
Last edited:
