TOPPING L50 Amp: Closer Examination

At first glance, the TOPPING L50 linear amplifier may look similar to the E50 DAC we just saw. This is of course deliberate, with companies making matching stack units inside and out to get users to purchase and use them together. As with the TOPPING E50, the L50 comes in four color options for the outer shell, with an anodized finish to the aluminium chassis. I again have the black version, which is also why I requested the black E50 for review shortly after it arrived. The TOPPING L50 is slightly larger than the E50, coming in at 16.6 x 13 x 4 cm, making it slightly wider in the back. It also weighs more at 545 g, but not to where it makes any practical difference once set up. There is of course no MQA sticker here, but the Hi-Res Audio badge makes a showing. Remember to peel off the sticker on the front as with the E50 to reveal the primary outputs and controls taking up the room of the display. This is still a glossy glass surface, and the cover on the volume knob is acrylic, both of which can get dirty and scratch over time, unfortunately.

The TOPPING L50 being a headphone amplifier first and foremost, it provides both a 1/4" (6.35 mm) and XLR output to drive your headphones. On the left is a tiny white power indicator LED followed by two physical switches, each with three positions. The first goes from off to selecting from among the inputs on the back, which may confuse customers thinking it instead toggles between the single-ended 1/4" and balanced XLR outputs on the front. The XLR output uses the same circuitry and provides the same power output as the 1/4" option, which goes to show that the XLR output is not a balanced connector and merely there for convenience with your cables. The second switch toggles between three gain modes (-14/0/+14 dB) as needed, which is great for driving sensitive IEMs and demanding headphones alike. There is also the expected volume knob rounding things off, which is fairly large and has a smooth finish. I would have liked a knurled wheel with discrete clicks to better indicate the volume steps, and there is otherwise a white mark on a red trim going from minimum to maximum. This red trim is present on the black or red TOPPING L50, with the blue variant having a blue trim and the silver variant going with a silver ring.


So while the headphone outputs are both single-ended in design, the inputs are where things differ with the TOPPING L50, as it may take a fully balanced signal courtesy 1/4" TRS connectors from, say, the E50 that also had them in the same position on the back. Next to these are the single-ended RCA connectors for input, and I was pleased to see the same set repeated for pass-through for when you want to connect the L50 to a set of powered speakers and use the E50/L50 stack as a preamp. Indeed, the TOPPING E50 is capable of being used as a preamp by itself, making the whole stack fairly versatile as a DAC offering volume control to desktop speakers in addition to headphones. The L50 needs to be in the off position for this, as turning it on turns off pass-through and preamp feature. There is a Type-C port on the back too, albeit for updating the firmware of the L50 with no other direct digital connections on board; it is quite nice to see, especially given TOPPING's recent history with the L30. Underneath, and rounding off the back, is the 15 VAC input that takes power from the wall adapter. All four RCA connectors come with the same protective covers on the back, so it does seem TOPPING would rather you connect the E50/L50 stack using balanced TRS cables after all.


As with the E50, we see four small hemispherical rubber pads on the bottom to raise the TOPPING L50. These do double duty by also providing some room for heat dissipation when using the two as a stack one above the other. Disassembly is similar in that there are screws on the back, but note that one is used to secure a daughter PCB holding the Type-C port, which will otherwise hang loose. The potentiometer on the volume wheel and other soldered connectors make it hard to take the entire PCB out for a closer examination, but I spotted a lot of finned aluminium heatsinks over the NFCA (Nested Feedback Composite Amplifier) modules using Texas Instruments OCC6H3T TPA6120A2 stereo headphone amplifiers that seem somewhat exclusive to TOPPING. This setup is based on the same linear amplifier design as in the higher-end TOPPING A30 Pro and makes for the extremely impressive THD+N and SNR numbers. I could go on about the claimed dynamic range, gain, noise levels, and channel crosstalk, all of which are exciting for folks who want them, but the biggest part outside of output power we will get to on the next page is the ultra-low output impedance of <0.1 Ω making this suitable for just about anything plugged into it, and certainly everything I have at my disposal.