As I described in my review of the Topping D30Pro desktop balanced DAC, it and this Topping A30Pro desktop headphone amplifier are clearly intended as a package. But, I noted, they are nonetheless both worthy products and I didn’t want the virtues of each lost in a mush of detail about the other, so I’m reviewing each separately.
So let’s dive into the Topping A30Pro.
- The Topping A30Pro is a high performance desktop headphone amplifier
- It is based on Nested Feedback Composite Amplifier modules used in Topping’s higher level models
- Rated output: 2 x 6 watts into 16 ohms, 2 x 5.5 watts into 32 ohms, 2 x 840mW into 300 ohms
- Rated signal to noise: -104dB @ 50mV, 1kHz or better
- Less than 0.00008% THD under realistic scenarios
- 20 to 40,000 hertz ± 0.05dB frequency response
- 1 ohm output impedance unbalanced, 0.2 ohm balanced
- 1 x stereo XLR balanced inputs, 1 x stereo RCA single-ended inputs
- 1 x stereo 6.35mm TRS balanced passthrough outputs, 1 x stereo RCA single-ended passthrough outputs
- 1 x 4-pin XLR balanced headphone output, 1 x 4.4mm balanced headphone output, 1 x 6.35mm unbalanced headphone output
- 5mm to 6.35mm adaptor included
- Internal power supply
- Available in black or silver finish
- 174mm wide by 46mm tall by 136mm deep
- 742 grams
- Price: $629
- Available at fine high fidelity retail outlets, and direct from distributor’s retail division here
More about the Topping A30Pro headphone amplifier
I didn’t attempt to convey the full wealth of specifications in the summary above, just some indicative ones. You see, these things are measured under a whole range of output conditions – various levels and into different headphone impedances – that can give widely different results. The signal to noise ratio above, for example is the worst of the specifications. The others are all better than that. If you want to dig into them all, they’re shown here.
Like the DAC, it has its power supply built in so that it plugs in with a standard power cable. The case is very nicely constructed of 2mm thick aluminium alloy on the top and sides, with the machined front panel up to 7mm thick. The top has a pleasingly set out collection of cooling holes, while there are also cooling slots on the side.
It does run fairly warm, so that air cooling is required. The basic amplifier design is Class A/B, and apparently there’s a higher than usual bias towards Class A, such that if you’re using headphones with an impedance of 250 ohms or more, the amplifiers run entirely in Class A. (See here for an explanation of amplifier classes.)
The Topping A30Pro is fitted with a front panel switch for selecting between the balanced and RCA inputs, and another for choosing one of three levels of gain. There is 14dB between each level. The low gain settings makes for safer use with extremely sensitive IEMs, while you can use high gain for low sensitivity headphones.
At the back there’s a switch for ground lift, which can help should any ground loop issues arise (these manifest as hum). I had no such problems during my time with the unit.
I should just add a quick note that things can get confusing for those new to this kind of gear, thanks to the use of the word “balanced” for two very different things on the Topping A30Pro. It has balanced inputs, which means that the two conductors carrying the signal for each channel are electrically separate to the shielding and ground. It also has balanced headphone outputs. That means that the left and right channels do not share any electrical connection, unlike with the regular 6.35mm and 3.5mm headphone connections.
I explain this in more depth here.
Listening with the Topping A30Pro headphone amplifier
I did almost all my listening with the A30Pro driven via Topping’s short XLR cables by the D30Pro. But I did dabble a little with some other devices, including several DACs with unbalanced outputs and with the Moon 280D streaming DAC. For headphones I mostly used Final Audio D8000 – they’re unbalanced – and Focal Elear headphones with a Cardas Audio Parsec headphone cable terminated in a 4.4mm balanced plug. But along the way I used every other set of ear gear that crossed my desk, including the Campfire Audio Honeydew IEMs, the 64 Audio Nio earphones, the Dunu Est 112 IEMs and the Grado White headphones. Plus several Sennheiser models, including my old HD 535 set from the late 1990s.
What the Topping A30Pro did with every set of them was take control and bring each of them to deliver their best performance. With effectively no distortion, no noise, no variation in the frequency response from the ideal, and with a low output impedance damping any untoward diaphragm movements and more than enough power for any contingency, how could it be otherwise?
I went through a wide range of genres – really, anything other than country. Whether it was high resolution Blue Note jazz from the 1960s, or gorgeously recorded modern jazz. Whether it was high resolution King Crimson or a standard resolution Schubert string quintet. Bach organ or harpsichord. It didn’t really matter. The Topping A30Pro simply delivered. Specifically, it imposed no character of its own on the sound. It simply revealed what was there.
My headphone amplifier test gear is only suited to standard – single-ended or unbalanced – outputs. With regard to the balanced outputs, from high performance from the unbalanced outputs we can infer at least equally high performance from the balanced.
First let’s look at output power. I use two test loads: 16 ohms and 300 ohms. I supplied my test signals using the companion Topping D30Pro DAC via the balanced connection. I found that into both loads I could max out the volume on all three of my test signals (100, 1002 and 10,000 hertz, peaking at 0dBFS) with no sign of clipping with the output gain set to low and medium.
For low gain, the unit delivered around 0.76 volts RMS into the 300-ohm load, and around 0.74 volts RMS into the 16-ohm load. That works out to 2mW and 34mW. I can’t really envisage any circumstances where you’d use high impedance headphones in this mode. That 34mW would drive 16-ohm IEMs to 15dB above their sensitivity rating. Which is plenty.
But if it isn’t, then you go to medium gain, which delivered (remember, this is clean, unclipped) 4 volts RMS into the 300-ohm load and 3.9 volts RMS into the 16-ohm load. That’s 55mW (or +17dB) into high impedance headphones, and 950mW (almost +30dB) into low impedance ones.
Still not enough? At high gain, the output remained unclipped even at the maximum volume setting when driving the 300-ohm load. It delivered at least 15.3 volts RMS for almost 800mW or 29dB above sensitivity rating.
Into the 16-ohm test load, the output clipped at around 8.8 volts RMS. Which meant it was delivering 4.9 watts, or nearly 37dB above sensitivity rating.
All of which means that the Topping A30Pro will easily drive any headphones that you’re ever likely to come across.
I calculated the output impedance at around 0.7 ohms, which is more than Topping specifies, but up there with the best in the field. It means that even if headphones have truly wild impedance curves, they will induce no noticeable frequency variations in the delivered signal. Which is exactly the behaviour that you want.
Finally, here’s the frequency response that I measured. Note, that’s less than 0.3dB down at 80kHz. More than adequate I should think:
The Topping A30Pro is a fine companion to the D30Pro, and a very respectable analogue headphone amplifier in its own right. It will provide excellent performance with just about any headphones.