Audio Science Review Reviews the TOPPING L50 Headphone Amp

This is a product review of the TOPPING L50 Headphone Amp, which is available for sale now on Apos.

This review was originally written and published on Audio Science Review by Amir Majidimehr on August 30th, 2021.

This is a review and detailed measurements of the new Topping L50 balanced (input) headphone amplifier. It was sent to me by the company and costs US $229. It will be announced shortly.

The industrial design of the L50 is different than older models with a plexiglass front:

While I like the red accent on the volume control knob, the contrast is low on the labels to read them easily. There is a plastic cover that has duplicate labels on it which are more legible. Fortunately there is not a whole lot here to remember as to need the labels.

The back side and power supply show more of a departure:

Instead of the usual switching power supply we now have a beefy AC transformer. As I have noted before, AC input makes it easier to generate positive and negative rails for the amplifier so I can see the motivation. Then again, the transformer is inefficient and quite large.

Up on top you see a connector you don't normally see on a pure analog amplifier: the USB-C for firmware upgrades! A supervisory processor handles protection which can be reprogrammed as needed. Indeed, during testing I pushed the unit hard with 12 ohm load well into clipping and it shut down with a sequence of LED lights. Once it cooled a bit, it enabled the device to function again.

The other change which we have seen recently from Topping is use of 1/4 inch input for balanced interconnections. They take up a lot less space than XLR so you can have the same rich set of connectivity including pre-amp in this small enclosure. 1/4 balanced is extremely popular in pro audio so there is plenty of cables and adapters for it if you are not situated currently to use them. And I believe a set of adapters come with the unit.

Topping L50 Measurements
There are many combinations here to test so I limited the input to balanced but measured both balanced and unbalanced headphone output. Let's start with balanced input:

And now RCA In:

Exceptional performance yet again, almost in the top position of our rankings for SINAD:

Here are our noise specs which are stellar:

This is what great SINAD does for you at the top of the class: incredibly low noise where you need it with sensitive IEMs:

Anyone who says SINAD is not important doesn't understand this dynamic, pun intended.

Frequency response is flat of course to beyond what we need:

The main business of a headphone amp is producing power though to drive more difficult headphones. So let's test that with 300 ohm load:

My standard for power output is 100 milliwatts and the L50 sails way past that which is great.

Let's switch to other extreme with 32 ohm load, emphasizing current delivery as opposed to voltage:

This is a ton of power coming out of this little box.

Sweeping the load and measuring power we get:

The main difference here compared to bigger brothers is that it clips with higher impedances whereas they don't. Up to nearly 7 volts there is no load dependency.

Finally here is our channel matching which is excellent for an analog control:

As usual your mileage may vary.

Listening Tests

Surprise, surprise, the L50 aces my subjective tests. What can I say. Whether I used the Sennheiser HD650 or Drop Ether CX, there was incredibly clarity, detail, authoritative bass, etc. My ears would scream before the amplifier even got barely unhappy as far as volume.

Conclusions

Hit after hit is the expression that always comes to mind when testing Topping products. Engineering done properly would be another saying. Compare this to many high-end products which barely get verified at all to see if they are what they think they are (transparent and well engineered). We do have some departure in form factor and functionality most of which are positive in my view. You get more choices and more to decide.

It is my pleasure to recommend the Topping L50.
Note: I have no commercial connection of any sort of shape with Topping or any other company for that matter. Don't spread rumors otherwise or I will personally show up and whack you in the back of the head! Many companies send me products and when they perform this well, they get my accolades.