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Topping LA90 Discrete Amplifier Review

Rate this stereo amplifier

  • 1. Poor (headless panther)

    Votes: 14 3.7%
  • 2. Not terrible (postman panther)

    Votes: 20 5.3%
  • 3. Fine (happy panther)

    Votes: 61 16.3%
  • 4. Great (golfing panther)

    Votes: 279 74.6%

  • Total voters


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
This is a review and detailed measurements of the Topping LA90 Discrete balanced stereo amplifier. It was sent to me by the company and costs US $799.
Topping LA90 Discrete Stereo Amplifier High performance review.jpg

The case is the same as the IC-based Topping LA90 which is fine with me given its high quality look and feel. The power switch doubles as input selector once the unit is on. Volume control can be bypassed using switch in the back:
Topping LA90 Discrete Stereo Amplifier High performance back panel balanced review.jpg

As before, power is provided by a hefty, 64 volt switching power supply rated at 4 amps (likely provides higher current in short bursts). The amplifier as you see is all balanced with three inputs. You have a selection of low and high gains (although the latter should really be called medium gain). It can be bridged and nicely tolerates even 4 ohm loads in that mode. Trigger is provided to enable one power switch to turn on a series of devices.

Note that this is a traditional amplifier and not class D. There is no remote so if you need that, you have to use a DAC/pre-amp with that capability.

Topping LA90 Discrete Measurements
There is a lot to measure here given the fact that we have dual gains and bridge mode. Let's work our way through it starting with low gain in stereo mode:
Topping LA90 Discrete Stereo Amplifier Low Gain Measurement.png

Incredibly, the LA90 Discrete matches the performance of its IC based unit, landing on its perch on top of all other amplifiers ever tested:
best stereo amplifier review 2023.png

Switching to high gain costs you a few dBs but you are still ahead the competition:
Topping LA90 Discrete Stereo Amplifier High Gain Measurement.png

So feel free to use this mode. Noise performance continues to be superb:
Topping LA90 Discrete Stereo Amplifier Low Gain SNR Measurement.png

Topping LA90 Discrete Stereo Amplifier High Gain SNR Measurement.png

Frequency response is flat of course and load independent:
Topping LA90 Discrete Stereo Amplifier Low Gain Frequency Response Measurement.png

Crosstalk is better than average amplifier but is a step down from the regular LA90:
Topping LA90 Discrete Stereo Amplifier Low Gain Crosstalk Measurement.png

Multitone showcases the superbly low distortion levels:
Topping LA90 Discrete Stereo Amplifier Low Gain Multitone Measurement.png

Let's see how we are doing in power department starting with 4 ohms:

Topping LA90 Discrete Stereo Amplifier Power into 4 ohm Measurement.png

We wind up good bit more power at 70 watts (vs 56 watts for normal LA90) while giving up nothing in spectacular noise and distortion department. Allowing for more distortion gets us more power:
Topping LA90 Discrete Stereo Amplifier High Gain max and peak power 4 ohm Measurement.png

8 Ohm performance follows the same path:
Topping LA90 Discrete Stereo Amplifier Power into 8 ohm Measurement.png

Tests so far have been at 1 kHz (other than multitone) so let's vary that and see what happens:
Topping LA90 Discrete Stereo Amplifier Power into 4 ohm vs frequency Measurement.png

In a word, wow! The amplifier simply doesn't care what frequency you throw out it! This is a quite a step ahead of normal LA90 which itself was state of the art.

Power on is silent but off may create a faint noise depending on your speaker sensitivity:
Topping LA90 Discrete Stereo Amplifier Low Gain Pop On and Off Noise Measurement.png

Warm up showed one channel struggling a bit but later I found the power connector not fully tight so maybe that was the cause:
Topping LA90 Discrete Stereo Amplifier Warm Up Measurement.png

Regardless, it behaved correctly after a minute.

Topping LA90 Discrete Bridged Measurements
As with normal LA90, bridge mode still provides superb performance:
Topping LA90 Discrete Stereo Amplifier Low Gain Bridged 4 ohm Measurement.png

Topping LA90 Discrete Stereo Amplifier Low Gain Bridged 4 ohm SNR Measurement.png

The name of the game is power though so let's see what we get into 4 ohm:
Topping LA90 Discrete Stereo Amplifier Low Gain Bridged 4 ohm Power Measurement.png

Notice how we get more power but distortion is nowhere to be found until we clip.

Topping LA90 Discrete Stereo Amplifier Low Gain Bridged 4 ohm max and peak Power Measurement.png

Wow! This makes a great case for using a pair of these amps. You get so much power out of each one, rivalling much larger amplifiers.

Reactive Load Testing
The LA90 has a very sharp clipping point. This means that it goes from vanishingly low distortion to full clipping. Combine this with aggressive protection circuit which shuts the unit off and you have the make up of a system that can't be measured in batch mode as my Powercube setup uses. If I set the voltage for 8 ohm load, then it causes the amp to shut down when driven at 4 ohm. Good news is that the amplifier doesn't care about reactive loads. Here are the results for 8 ohm for example:
Maximum Output
12:13 AM
Maximum Output Level Results
Selected Load    Ch1 (Vrms)    Ch2 (Vrms)    
8 Ohm; 60 deg Capacitive    21.2    21.3    
8 Ohm; 30 deg Capacitive    21.1    21.2    
8 Ohm; 0 deg Resistive    21.0    21.0    
8 Ohm; 30 deg Inductive    20.2    20.3    
8 Ohm; 60 deg Inductive    20.9    21.0

I could not get a similar output at 4 ohm due to limitation of the instrumentation as stated above. But if I drove the parameters manually, I could get it to tolerate reactive loads just as well.

Selecting 2 ohm caused the protection circuit to kick in. I didn't have time to mess with that.

I spent nearly 2 hours trying to get this test done with the amplifier being pushed to clipping and shut down probably 50 to 100 times. Even though the case got pretty warm, the amp continued to function without complaining.

Traditionally in high-end audio when a company says they are using discrete designs, I get prepared for bad performance. Topping once again proves that this is no barrier for their designers. The discreate LA90 not only matches the exemplary performance of the IC based LA90, but betters it in power handling, producing more power (a needed feature). Pushing noise and distortion down in our top tier performance is very hard but Topping has no problem maintaining its significant lead over even best of the best amplifiers. Their skills and execution in this regard leaves me speechless.

Needless to say, it is my absolute pleasure to add Topping LA90 Discrete to my recommended list. Today is a happy day! :)

P.S. Power amplifiers are least reliable audio products (due to high currents and voltages involved). New designs sometimes need to prove themselves in this regard. So if you are risk averse, please don't be the first to purchase this amplifier.

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/


Staff Member
CFO (Chief Fun Officer)
Feb 13, 2016
Seattle Area
Thanks for the review. As a non-electronic engineer type.. Is there a reason one might choose the IC version over the discrete version?
This version is superior in every regard for the same money. I believe it will be replacing the IC based one soon if it has not already.


Addicted to Fun and Learning
Forum Donor
Jul 19, 2020
Commonwealth of Massachusetts
Virtuoso performance, essentially a game over for many other amplifiers. It is early in the morning, coffee has not kicked in yet: how does it quadruples the power instead of doubling it in bridged configuration?


Active Member
Jul 25, 2020
I havent every looked at Topping amps but it would make sense to release this as a pure power amp (with the mono/stereo and gain switches but one input and no volume control).

Does/will such a beast exist?

It already is when you bypass pre-sektion.


Major Contributor
Jan 27, 2020
Suffolk Coastal, UK
Of course all you newbies will be using sources with balanced outputs, but what of us oldies with some single ended RCA sources? I seem to recall the previous model was truly hobbled when used that way via properly configured interconnects...


Lackey, Second Order…..for now.
Forum Donor
Jan 3, 2021
Smashing out 3 complete Reviews in one day! Your a Machine and we can only marvel at your work ethic and drive for perfection. A Trifecta day Boss. Careful you might spoil us now. As always thanks for so much information for so little. Not a better deal to be had in the world of Audio Product Testing and Analysis focused on what the Consumer needs to know to make the absolute best purchasing decisions.

Saint Amir :cool:


New Member
Mar 13, 2023
absolute monster of a unit! I hope there's going to be more competition in this price range and lower price ranges.
Thanks for the review.


Major Contributor
Sep 8, 2021
Couple of these could come handy to drive my mid-high section as long as they stand my standard couple of years time test without multiple failure reports.

Thanks Amir!
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