This is a "naked" review and measurements of the LH Labs Go2Pro DAC and headphone amplifier. I say naked because in in the interest of time, I am posting its results by itself. I am hoping by now you all are familiar with the norms in my measurements and can see its fidelity. Actually there is one measurement that includes a comparison.
I can't find its retail price but it is on sale now with 20% off at $480 on LH Labs website. So quite pricey. The unit is on kind loan from a member.
Anyway, this is a self-powered device (although I tested it while connected via USB) and includes a 3,200 mah battery. That combined with a metal enclosure makes for one hefty device.
I find the user interface maddening. There is a simple on/off switch but then the "up" volume control is overloaded as meaning both extra gain, and filter??? I confess I could not figure it out. Pushing the up volume to max did light up one of the many colored LEDs which I assumed meant high-gain. The lights are surface mount LEDs and as tiny as they can get. Seemingly they are wasted for DSD rates??? I told you that I found the interface maddening. Someone with more patience than me may be able to figure it out.
Fortunately the device is UAC 2 compliant so worked plug-and-play with Roon/Windows WASAPI interface for bit-exact transmission.
BTW, one thing about the name: they seem to sometimes put a space after "GO2" and sometimes not. I followed their lead by mixing the two ways of writing it just the same.
Here are the formats it advertises as supporting to Roon:
So pretty extensive.
Size-wise the unit is almost as wide as my Samsung S8+ but much less tall. So you could rubber band it to the back of it.
I am sure you are anxious to see the measurements so let's get into that. If you are not familiar with my measurements, I suggest reading my tutorial on audio measurements here: https://www.audiosciencereview.com/forum/index.php?threads/understanding-audio-measurements.2351/
Measurements
Let's start with simple frequency response:
So we are down 1/4 of a dB at 20 kHz at 48 kHz sampling. I assume this is with the default filtering. I did not try to change it per my introduction.
Next let's look at jitter:
Noise floor is very good and low. We see a number of little spikes but they are all at -130 dB down so not an audible concern.
Let's look at distortion products:
For reference here, I have included the "speaka" USB thumb DAC. See review here: https://www.audiosciencereview.com/...-speaka-usb-dac-and-headphone-amplifier.2423/. That is a nice bargain of a DAC at around $30. Alas it doesn't do as well as the Go2 Pro.
The above measurement is in maximum gain mode. We see a knee of rising distortion which we can decipher much more easily in the spectrum of distortion:
Wow. Look at the high amount of harmonic distortion in red when we are in high-gain/max volume mode. Just dropping the volume one notch/disabling high-gain mode results in far better performance.
Let's look at linearity now:
Performance here is pretty good. My arbitrary 0.1 dB of deviation occurs at -110 dB and 18 bits of resolution. Response past that up to -120 dB is still very good.
Likewise our -90 dB sine wave looks pretty reasonable:
Switching from DAC testing to headphone testing, I measured the output impedance a very low 0.5 ohm.
This means that it should have no effect on the frequency response of the headphone even if that latter is pretty low.
Now let's look at power versus distortion. This is all in high-gain mode with a 400 Hz tone, both channels driven:
I must say, these are lower than I expected. Max power is naturally at 33 ohm load with onset of clipping at 40 milliwatt. I tried to find specs for power but could not find any. If anyone knows them, I appreciate seeing what they state.
So enough with measurements, let's see how it sounds.
Listening Test
This being a naked review, I didn't know what to test it against. So I just picked my laptop (HP z series), thinking it is a decent representation of a portable player, cell phone, etc.
Usually I expect outboard amplifiers to clean the clocks of my laptop with respect to power but such was not the case. Using both Sennheiser HD-650 and Hifiman HE400i, I could roughly get the same volume out of my laptop as I could with the Go2 Pro. Yes, in high-gain mode the Go2 Pro was somewhat louder but I did not like that mode. Dropping down one notch would give me decent volume but with no headroom.
Subjectively, in AB testing, the LH Go2 Pro had a bit more detail and resolution as compared to my laptop. So it does something good. I just wished it had more power.
Switching to Grado SR60e provided more power and on pop and rock, it was plenty loud. But once again, on audiophile recordings that avoid the peaks, the volume was just enough.
Conclusions
The LH Labs GO2 Pro DAC and headphone amplifier seems solidly built, both in performance and heft of the unit. Standard DAC measurements don't indicate any faults in low-gain mode. High-gain mode though is a distortion factory and one that I would not use. The user interface is also confusing to impatient people like me. Fidelity is good but in my opinion, the output power is insufficient for any power hungry headphones.
The biggest issue in my opinion is the high cost at over $500 retail. For that, I would really want my headphones to flap in the air with power.
I will be testing the iFi self-powered DAC that I have in the future. Will be interesting to see how well it does in the same tests.
As always, questions, comments, corrections, jokes, etc. are all welcome!
----
If you like this review, please consider donating funds for these types of hardware purchase using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
I can't find its retail price but it is on sale now with 20% off at $480 on LH Labs website. So quite pricey. The unit is on kind loan from a member.
Anyway, this is a self-powered device (although I tested it while connected via USB) and includes a 3,200 mah battery. That combined with a metal enclosure makes for one hefty device.
I find the user interface maddening. There is a simple on/off switch but then the "up" volume control is overloaded as meaning both extra gain, and filter??? I confess I could not figure it out. Pushing the up volume to max did light up one of the many colored LEDs which I assumed meant high-gain. The lights are surface mount LEDs and as tiny as they can get. Seemingly they are wasted for DSD rates??? I told you that I found the interface maddening. Someone with more patience than me may be able to figure it out.
Fortunately the device is UAC 2 compliant so worked plug-and-play with Roon/Windows WASAPI interface for bit-exact transmission.
BTW, one thing about the name: they seem to sometimes put a space after "GO2" and sometimes not. I followed their lead by mixing the two ways of writing it just the same.
Here are the formats it advertises as supporting to Roon:
So pretty extensive.
Size-wise the unit is almost as wide as my Samsung S8+ but much less tall. So you could rubber band it to the back of it.
I am sure you are anxious to see the measurements so let's get into that. If you are not familiar with my measurements, I suggest reading my tutorial on audio measurements here: https://www.audiosciencereview.com/forum/index.php?threads/understanding-audio-measurements.2351/
Measurements
Let's start with simple frequency response:
So we are down 1/4 of a dB at 20 kHz at 48 kHz sampling. I assume this is with the default filtering. I did not try to change it per my introduction.
Next let's look at jitter:
Noise floor is very good and low. We see a number of little spikes but they are all at -130 dB down so not an audible concern.
Let's look at distortion products:
For reference here, I have included the "speaka" USB thumb DAC. See review here: https://www.audiosciencereview.com/...-speaka-usb-dac-and-headphone-amplifier.2423/. That is a nice bargain of a DAC at around $30. Alas it doesn't do as well as the Go2 Pro.
The above measurement is in maximum gain mode. We see a knee of rising distortion which we can decipher much more easily in the spectrum of distortion:
Wow. Look at the high amount of harmonic distortion in red when we are in high-gain/max volume mode. Just dropping the volume one notch/disabling high-gain mode results in far better performance.
Let's look at linearity now:
Performance here is pretty good. My arbitrary 0.1 dB of deviation occurs at -110 dB and 18 bits of resolution. Response past that up to -120 dB is still very good.
Likewise our -90 dB sine wave looks pretty reasonable:
Switching from DAC testing to headphone testing, I measured the output impedance a very low 0.5 ohm.
This means that it should have no effect on the frequency response of the headphone even if that latter is pretty low.
Now let's look at power versus distortion. This is all in high-gain mode with a 400 Hz tone, both channels driven:
I must say, these are lower than I expected. Max power is naturally at 33 ohm load with onset of clipping at 40 milliwatt. I tried to find specs for power but could not find any. If anyone knows them, I appreciate seeing what they state.
So enough with measurements, let's see how it sounds.
Listening Test
This being a naked review, I didn't know what to test it against. So I just picked my laptop (HP z series), thinking it is a decent representation of a portable player, cell phone, etc.
Usually I expect outboard amplifiers to clean the clocks of my laptop with respect to power but such was not the case. Using both Sennheiser HD-650 and Hifiman HE400i, I could roughly get the same volume out of my laptop as I could with the Go2 Pro. Yes, in high-gain mode the Go2 Pro was somewhat louder but I did not like that mode. Dropping down one notch would give me decent volume but with no headroom.
Subjectively, in AB testing, the LH Go2 Pro had a bit more detail and resolution as compared to my laptop. So it does something good. I just wished it had more power.
Switching to Grado SR60e provided more power and on pop and rock, it was plenty loud. But once again, on audiophile recordings that avoid the peaks, the volume was just enough.
Conclusions
The LH Labs GO2 Pro DAC and headphone amplifier seems solidly built, both in performance and heft of the unit. Standard DAC measurements don't indicate any faults in low-gain mode. High-gain mode though is a distortion factory and one that I would not use. The user interface is also confusing to impatient people like me. Fidelity is good but in my opinion, the output power is insufficient for any power hungry headphones.
The biggest issue in my opinion is the high cost at over $500 retail. For that, I would really want my headphones to flap in the air with power.
I will be testing the iFi self-powered DAC that I have in the future. Will be interesting to see how well it does in the same tests.
As always, questions, comments, corrections, jokes, etc. are all welcome!
----
If you like this review, please consider donating funds for these types of hardware purchase using Patreon (https://www.patreon.com/audiosciencereview), or upgrading your membership here though Paypal (https://audiosciencereview.com/foru...eview-and-measurements.2164/page-3#post-59054).
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