"History is made": Audio Science Review on the TOPPING LA90

Note: This article is based upon the video "Topping LA90 Review (Integrated Amplifier)" made by Amir Majidmehr on Audio Science Review and is printed here in partnership with Audio Science Review. The review was originally posted on April 25th, 2022. It has been reproduced here in its entirety. You can purchase the TOPPING LA90 on Apos Audio.

This is a review and detailed measurements of the Topping LA90 integrated amplifier. It was sent to me by the company and costs US $800.

I must say, this is one interesting industrial design. Everything oozes style despite the diminutive package. This aspect continues in the operation of the unit with the sound of the relays solidly clicking indicating something good is going to happen.

Here is the side view:

While quite solid, you can pick it up with one hand. The small size is aided by a massive external switching power supply:
Here are its ratings:
Back to the unit, you can see three balanced inputs. Volume control can be bypassed although I did not do so for my testing. You can also operate LA90 in bridged mono mode. There is also 12 volt trigger.

There are to gain settings. One at 10 dB and another at 20 dB (nominal).

Topping LA90 Measurements
These are non-bridged mode measurements. Bridged setup follows this section. Let's start with our dashboard of 5 watts into 4 ohm in low gain mode:
I don't need to tell you that this is a stunning level of achievement. We have a power amplifier producing almost the same SINAD as a state of the art DAC! Using this number, LA90 grabs the top spot with ease with a nice gap to boot:
Here it is zoomed:
You might be thinking that it can only do so with low gain but that is not true. Even in high gain performance is spectacular:

It would still achieve top spot in our rankings and achieve full audible transparency.

Not only is distortion vanishingly low, so is noise level:

Frequency response is flat and wide as expected:

Being class AB design, it has no load dependency.

Crosstalk is incredibly good although it loses a tiny bit relative to last champ of amplifiers:

Multitone test shows the very low distortion levels:
Let's see how much power we have:
So power is modest in non-bridged mode. But note how good the high gain mode is so I would feel just fine using that for operation of the unit if you need to. Allowing distortion to rise to 1% naturally gets us more power:
Here is 8 ohm:
Oops. "High Power" should be "High Gain."

Changing frequencies shows the same excellent performance:
Despite being pushed deep into clipping, the amplifier did not complain until I got to 20 Hz where its over temperature shut it down.

Finally, you don't need any warm up:
Topping LA90 Bridged Mode Performance
A shorting wire is provided to connect the two negative speaker bindings together allowing bridged mode from the top two posts. Here is our dashboard again:
Performance is still exceptional. Here is our SNR:

Due to more power available now, we cross the amazing 140 dB SNR threshold. What this says is that even if you play at 140 dB, the noise level will be at or below threshold of hearing! Of course there is not enough power there to do that but basically you know that noise is not part of the equation with LA90 as even 5 watt measurement hits below threshold of hearing.

We want to know the power increase though so here it is (with 8 ohm which is the minimum impedance):

Now we get good bit of power at 95 watts with almost no penalty relative to non-bridged mode. Notice the massive gap as far as noise floor relative to Purifi amplifier.

Allowing for 1% distortion we get:
Here is the super wideband spectrum of the amplifier while producing 5 watts:
Edit:
Power Tests at 2 Ohm (Stereo) and 4 Ohm (Bridged)
Requests were made to test the amplifier beyond its minimum load impedance specs. Let's start with 2 ohm load while driving one channel in stereo mode. Dashboard still shows superb performance:
Let's now sweep the power:
You don't get extra power relative to 4 ohm but the amplifier was stable and did not even go into protection.

Now let's switch to Bridged mode (both amplifiers driven in differential mono) and run our power sweep again:

Now we see the amplifier "doubling down" producing nearly 200 watts into 4 ohm. Again, the amplifier was well composed and kept driving into clipping region without complaining, or shutting down.

Again, the above tests are beyond the amplifier specifications and tests I never run as such.

Conclusions

It is clear that Topping engineers are bringing their expertise in designing ultra low noise and distortion in headphone amplification to power amplifiers. As such, they have outdone every amplifier I have measured in that regard, getting ahead to capture the #1 position with a large gap to #2 choice.

The amplifier is not for everyone though. Power level is modest as compared to competitors. And you have that large external power supply. My wish is another version of this amp with built-in power supply, motorized volume control with bridge mode standard. For now, we need to celebrate one of the most important development in delivering transparent, high fidelity amplification to audiophiles in a very attractive package.

It is my absolute pleasure to recommend the Topping LA90. History is made on this day folks!