Setup and Performance

Unlike the Atom DAC+/Amp+ stack, there is no need to consider having the DAC above the amplifier here. The beefier construction means there is no way the cables on the back or front will tip things over, so go ahead and place the TOPPING L50 over the E50 as seen above. This creates more room for heat dissipation from the amplifier, which is obviously the more power-hungry of the two. I will also say that the inner heatsinks and aluminium chassis make for a setup without any heat-related issued even over longer sessions. Based on the feature set, I would certainly go with a set of 1/4" TRS interconnects, such as TOPPING's own TCT1 set bundled with the E50 and L50 if bought together. I did not have those or any 1/4" TRS cables on hand, so I went with the same RCA interconnects as in the JDS Labs Atom stack review. TOPPING sells RCA interconnects as well, and those are more likely to be bundled with the E50 and L50 combo. This makes for single-ended input from the TOPPING E50 to the L50, and the two stack up nicely as seen above.


Next comes connecting the two USB cables from the E50, as well as the AC power adapter feeding the L50. These three cables are the bare minimum for using the E50 and L50 stack with a desktop to drive headphones, and you may want to consider having the pass-through options to use the stack as a preamp to powered desktop speakers, or even the coax or optical input of the E50. The three used above can be cable-managed well enough courtesy the thin cables, and turning the stack on now also shows the display of the E50 in its orange glory. I have no idea why TOPPING went with orange as it clashes with all the color options for the E50/L50 stack and can be cumbersome at night or in low-lit environments. Regardless, this is where you find out how little the E50 can do with that single button next to the display—it only cycles through the various inputs. The display turns itself off after a minute of inactivity, so that's something at least. Note that the -30 dB display corresponds to the volume control setting by default, which makes for a relatively quiet setup if the L50 is also in low gain (-14 dB) mode. So don't be surprised if things are not audible to begin with as that's where the two volume controls on the E50 and L50 in addition to the three gain modes on the L50 come in.


There is no need to install drivers for use with Windows 10 or 11. The TOPPING E50 is recognized automatically and set up as a speaker output by default with nothing connected to the headphone jack. This allows for up to 32-bit 384 kHz PCM playback in Windows, which the display of the E50 shows. Of course, this is assuming your PC is a compatible UAC2 device. It's when used with consoles in particular that you need to rely on UAC1, and you may need a fallback UAC1 cable for that. If you use the coax or optical input, playback is limited to "only" 24-bit/192 kHz, with the respective mode shown on the display, and the playback setting seen for a second before defaulting back to the volume setting.



Earlier Windows versions, including Win 7, which I know some are still on, do not have native XMOS decoding support, which would have you download the XMOS drivers, whose installer is found here. These drivers also enable WASAPI exclusive mode as an option in the player of your choice instead of just ASIO, which holds true in Windows 10/11 as well. Other options are now available too, including buffer size for the E50 over ASIO.


As seen above, JRiver had no issues detecting both WASAPI and ASIO options, and TOPPING even has a guide on configuring the E50 for best playback with the likes of Foobar and JRiver. You can always check the driver status as it pertains to the controlled hardware to ensure it is indeed the TOPPING E50 being configured. As seen above, the XMOS drivers allow for 16 and 24-bit playback. My default setup was 32-bit audio over JRiver, with volume in Windows 10 set to ~95%, and I then set the sampling rate to an integer multiple of the source-file quality, as random issues may arise if it deviates from this integral multiplier. Many companies suggest as much; for example, use 192 kHz playback with 48/96/192 kHz audio files. Of course, the TOPPING E50 brings with it DSD playback too, in addition to MQA rendering, which may or may not interest you with all the ongoing drama. If it does, note that full rendering and MQA unfolding is only available with USB input, and it will once again be displayed.


Here is an example setup with the HarmonicDyne Poseidon (review coming sooner than later) connected to the TOPPING L50 using the stock XLR cable. Using RCA interconnects, the L50 was connected to the E50, which was in turn connected to my PC via the USB cable. As such, I set the first switch on the L50 to SE for the single-ended input, and then set the gain switch to medium. At this point, turning the volume knob to about 3 o'clock was sufficient for a quick test, but the operating conditions weren't necessarily the best because the E50 was still set to -30 dB in its output. This is where the remote control came in handy, as I quickly changed the volume of the entire stack on the E50 itself. It's the easiest way forward for when you, say, have the stack placed somewhere near the back of your desk. The remote control also allows for quickly changing inputs and outputs from the E50, as well as adjusting the brightness of the display, among other things. This is also the best way to control speaker volume when using the stack as a preamp. I certainly urge users to use the remote.

Given this is predominantly a headphone stack, what matters the most is how clean the signal output is and how much power is provided to drive headphones. The most useful metric in this regard is the immense 3.5 W per channel maximum continuous power rating at 16 Ω with a THD+N below 0.1%, which is far too much power for just about any set of headphones or IEMs with 16 Ω impedance. Indeed, IEMs tend to more often fall into this range, and are far more sensitive than headphones, so you would absolutely need to start at low gain and volume on the E50/L50 set to the minimum before slowly increasing things lest you blow up the IEM drivers and potentially damage your ears. That said, I certainly would not get this stack purely for IEMs, including some of the more demanding planar driver IEMs. But if you do occasionally want to use these with IEMs, the low output impedance of under 0.1 Ω and clean power come in handy, as I did not have any hiss with most of the IEMs I have here; exceptions were the Campfire Audio ones that seem to hiss with just about anything in standby anyway.

As expected, output power goes down as impedance increases. However, with 2.8 W at 32 Ω, 2 W at 64 Ω, 0.54 W at 300 Ω, and 0.29 W at 600 Ω, numbers are still high. You can find a very handy power calculator for headphones here, which confirms that the E50/L50 stack can drive just about any headphone well enough. Current output is also sufficient to meet the needs of those who profess high current amplification for the likes of planar driver headphones, and I am inclined to test this combo with the most demanding headphones (think HIFIMAN Susvara or HE6 series) as and when I get the chance. TOPPING of course has higher power output amplifiers in its A-series, with the A30 Pro able to put out 6 W per channel in single-ended operation and the flagship A90 capable of a massive 7.6 W in balanced mode. Keep in mind that both the 1/4" and XLR outputs are single-ended, so feel free to use either based on your cable type. I should also point out that the E50 and L50 circuitry were designed together, and for those wanting an integrated amplifier to drive passive speakers, the newly released PA5 power amplifier is intended to be used with the E50.

As with most such linear amplifiers, the TOPPING E50/L50 stack is acoustically transparent. This means the sound signature of your headphones, IEMs, and speakers will not be changed when driven through the stack. It was the same with the two previous JDS Labs reviews, as well as most portable sources I have tested to date. There is no felt harmonic disorder, be it second or third-order harmonics where the likes of tube amplifiers make their presence felt. As such, don't expect this stack to add any coloring to the tonality of headphones, which to many is music to the ears as this stack can drive more demanding headphones without changing the frequency response or tonality, and technicalities come off untouched as well. This is why I am not even showing a frequency response measurement this time around, noting that everything measured identically to my reference sound card, as well as the JDS Labs Element II from before.

There were obvious improvements in comparison to my laptop's own Realtek ALC3266 chipset throughout the frequency range of all tested headphones and earphones, and this is before the speaker option with the preamp comes in. The E50/L50 stack cleans up the sound output and provides for a fantastic listening experience. Note that I also tested this with some motherboards, but could not easily get my PC near the noise-dampened chamber where testing is done. With some higher-end motherboards that boast great onboard audio, I was not able to discern a difference between the integrated audio circuit and TOPPING E50 on most files, but orchestral music recorded in FLAC still showed an improvement up to 192 kHz PCM playback. My Tidal subscription had just run out, and I have no plans to renew it for MQA testing while trialing Qobuz for my streaming needs instead. Using the E50 in ASIO mode with JRiver and DSD playback also worked smoothly as shown before, so you may want to install those drivers if you are also interested. I also acknowledge that testing a DAC or amplifier requires an oscilloscope at the very least, and takes a much more expensive audio analyzer, but I do not have access to one at this time.