This is a review and detailed measurements of the XPA-700 battery operated portable DAC and balanced headphone amplifier. It is on kind loan from a member and costs US $508 including Prime shipping. It seems to be a Japan product though and not directly sold in US.
The XPA-700 is one of the most stout and rugged looking portable headphone amp I have seen. It reminds of what a field recorder would look like:
There are controls and jacks everywhere which fortunately are nicely labeled so not hard to navigate. Here is the front:
There is a balanced headphone jack in the back with the 4-pin configuration. There are options for resampling audio to higher rates (which made no difference in my testing), choice of filters, etc.
The solid feel is great for desktop use but I don't know about the merits of that in a portable product where weight matters.
USB DAC Audio Measurements
There is a micro-USB jack on the back which allows the XPA-700 to be used as a DAC. Combined with a line out socket and switch, it made testing it as a straight DAC easy:
Alas, this is disappointing performance. SINAD which is a combined measure of noise is just 93 dB which is shy of what we need to resolve CD's 16 bit dynamic range let alone high-resolution audio. Ranking then among all products with DACs in them is not good:
Noise performance is good though:
Intermodulation distortion versus level is good and could have been excellent if distortion had not taken over toward the end:
32-tone test resembling "music" is at a lower level so shows better intermodulation distortion:
I tested jitter with or without resampling to 192 kHz and the latter reduced jitter visually (but not materially as far as audibility):
The broad skirt around our main tone shows fair bit of random jitter which would have been good to not be there.
Linearity which is a measure of precision is nailed to 20 bits or -120 dB:
Headphone Amplifier Measurements
Let's start with our dashboard of feeding the amplifier a 2 volt signal and see what comes out when the volume is adjusted to pass the same level:
This is worse than the DAC portion unfortunately. Third harmonic is dominant and quite high as desktop amplifiers go these days.
Bandwidth is quite wide and flat:
Noise performance at the same 2 volts is not bad (left) but when you lower the volume, it degrades fair bit:
The latter lands the XPA-700 in the middle of the pack:
And means that you may hear some noise or hiss with very sensitive headphones or IEMs.
Let's hook up a 300 ohm load to the unbalanced output representing a high impedance headphone and see how much power, noise and distortion we see:
Well, even in high gain we don't get a lot of power. My standard for desktop amplifiers is 100 milliwatts and at 20 milliwatts, we are well short of that. Fortunately if you can use the balanced output, you get four times as much power:
Switching to a 33 ohm load we get:
The high output impedance of 12 ohm causes a lot of losses here. 111 milliwatts of power is not a lot and the high impedance means frequency response of some headphones will change.
Channel balance as you rotate the volume control is not great:
Sorry, did not have time to perform any listening tests.
Conclusions
While it is hard to get great performance in a portable form factor, that isn't what we expect when we pay $500 headphone amp and DAC. The XPA-700 has the look of a serious device but performance is middling and not impressive. It is not terrible though so you get to decide if its form factor, functionality, performance and price fits your needs. It does not for me so can't recommend it.
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As always, questions, comments, recommendations, etc. are welcome.
Freight company came today to deliver a large speaker for testing. As usual, would refuse to come down our 1/3 of a mile driveway. So I told him I would come up with my car. He asked if I had a truck. I said no. He was shocked. We managed to stuff the monster speaker in my car but I really need a truck. Not one of those cheap ones mind you. It has to be a luxury one to fit my style of living. So I appreciate if you all start to donate seriously toward this worthy cause using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
The XPA-700 is one of the most stout and rugged looking portable headphone amp I have seen. It reminds of what a field recorder would look like:
There are controls and jacks everywhere which fortunately are nicely labeled so not hard to navigate. Here is the front:
There is a balanced headphone jack in the back with the 4-pin configuration. There are options for resampling audio to higher rates (which made no difference in my testing), choice of filters, etc.
The solid feel is great for desktop use but I don't know about the merits of that in a portable product where weight matters.
USB DAC Audio Measurements
There is a micro-USB jack on the back which allows the XPA-700 to be used as a DAC. Combined with a line out socket and switch, it made testing it as a straight DAC easy:
Alas, this is disappointing performance. SINAD which is a combined measure of noise is just 93 dB which is shy of what we need to resolve CD's 16 bit dynamic range let alone high-resolution audio. Ranking then among all products with DACs in them is not good:
Noise performance is good though:
Intermodulation distortion versus level is good and could have been excellent if distortion had not taken over toward the end:
32-tone test resembling "music" is at a lower level so shows better intermodulation distortion:
I tested jitter with or without resampling to 192 kHz and the latter reduced jitter visually (but not materially as far as audibility):
The broad skirt around our main tone shows fair bit of random jitter which would have been good to not be there.
Linearity which is a measure of precision is nailed to 20 bits or -120 dB:
Headphone Amplifier Measurements
Let's start with our dashboard of feeding the amplifier a 2 volt signal and see what comes out when the volume is adjusted to pass the same level:
This is worse than the DAC portion unfortunately. Third harmonic is dominant and quite high as desktop amplifiers go these days.
Bandwidth is quite wide and flat:
Noise performance at the same 2 volts is not bad (left) but when you lower the volume, it degrades fair bit:
The latter lands the XPA-700 in the middle of the pack:
And means that you may hear some noise or hiss with very sensitive headphones or IEMs.
Let's hook up a 300 ohm load to the unbalanced output representing a high impedance headphone and see how much power, noise and distortion we see:
Well, even in high gain we don't get a lot of power. My standard for desktop amplifiers is 100 milliwatts and at 20 milliwatts, we are well short of that. Fortunately if you can use the balanced output, you get four times as much power:
Switching to a 33 ohm load we get:
The high output impedance of 12 ohm causes a lot of losses here. 111 milliwatts of power is not a lot and the high impedance means frequency response of some headphones will change.
Channel balance as you rotate the volume control is not great:
Sorry, did not have time to perform any listening tests.
Conclusions
While it is hard to get great performance in a portable form factor, that isn't what we expect when we pay $500 headphone amp and DAC. The XPA-700 has the look of a serious device but performance is middling and not impressive. It is not terrible though so you get to decide if its form factor, functionality, performance and price fits your needs. It does not for me so can't recommend it.
-----------
As always, questions, comments, recommendations, etc. are welcome.
Freight company came today to deliver a large speaker for testing. As usual, would refuse to come down our 1/3 of a mile driveway. So I told him I would come up with my car. He asked if I had a truck. I said no. He was shocked. We managed to stuff the monster speaker in my car but I really need a truck. Not one of those cheap ones mind you. It has to be a luxury one to fit my style of living. So I appreciate if you all start to donate seriously toward this worthy cause using : https://www.audiosciencereview.com/forum/index.php?threads/how-to-support-audio-science-review.8150/
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