Pros
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Excellent build quality -
Compact size for desktop product
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Fairly powerful
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Bypassed RCA output
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Great sound quality
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Opamps can be swapped
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Reasonably Priced
Cons
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Output impedance a bit high -
No preamp function
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Gain switching not ideal
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Slight hissing with sensitive IEMs
Bottom Line
Table of Contents
Specs
- Outputs : 6.5mm, 3.5mm, 2.5mm balanced
- Frequency response : 20-40kHz
- SNR : 123dB
- THD+N : 0.0006% (unbalanced) / 0.0004% (balanced)
- Gain : Low (0dB) / High (9dB)
- Output Impedance : 4.7Ω (unbalanced) / 9.4Ω (balanced
- Output power : 1110mW @ 32Ω (unbalanced) / 2200mW @ 64Ω (balanced)
Design
When looking at the A50, the first thing that it reminded me of was the Mac Mini due to the squarish profile with the rounded corners. Of course, there is the addition of some bevelled edges, but overall it has a fairly similar look.
It’s more compact than a Mic Mini, though, and the images found online really don’t give you a real idea of just how compact this amplifier is for a desktop-grade headphone amp. I specifically say this with reference to a desktop unit because whilst it is surprisingly compact for this type of device, it’s still a fair amount larger than what you’d expect from a portable headphone amp.
Another plus is that the A50 doesn’t just look somewhat similar to the Mac Mini, but the build quality of this unit is also exceptionally good. Weighing in at just shy of 460g (1.01lb), it has a really nice heft to it which helps to give it a premium feeling. The outer case is machined out of a single block of aluminium, but the bottom plate can be unscrewed which will then give you access to all of the parts inside. And yes, that does include both of the opamp chips, so you can swap out and upgrade them if you’d like.
Along the front of the A50 are all of the controls and the headphone outputs. The power button is the only button on the entire device, and is also used to switch between the high and low gain. Speaking of which, there is a white LED to indicate which gain mode the amp is in. This is, of course, very helpful since you wouldn’t want to plug in your super sensitive IEMs when the amp is in high gain mode. What isn’t helpful is how you switch between the gain modes. As mentioned, the power button is used for this, and a single press is all that is required to switch between the gain modes. Whilst that is simple, the problem is that it also means that you can very easily switch from low to high gain unintentionally when you attempt to turn the amp off. In order to switch the amp off, you need to hold the power button in for about 1 second. This is just something you’ll need to be really careful about.
For the headphone outputs we are given a choice of 6.5mm and 3.5mm unbalanced outputs, as well as a 2.5mm balanced output. The unbalanced outputs are capable of producing up to 1110mW per channel into a 32Ω load, whereas the balanced output can take things up to 2200mW per channel into a 64Ω load. That really is not a small amount of power, and it’s especially impressive given how compact the A50 is.
There are just two downsides here, with the first being the output impedance. At 4.7Ω for the single-ended outputs and 9.4Ω for the balanced output, this is something which might affect the frequency response of your headphones. This will of course not be much of a problem for high-impedance headphones, but those ultra-low-impedance IEMs could experience a significant change (for better or worse), especially from the balanced output. This is not something that bothered me personally, but it’s just something you might need to keep in mind. Secondly is that there is some hiss produced when using low-impedance/high-sensitivity IEMs. For reference, I used the Dunu DK-3001 to check this because it’s got an impedance of just 13Ω and a sensitivity of 110dB, and I could hear some hiss when I plugged it into the A50. It was very soft though, and I really couldn’t hear any of it when playing music. Something like the Campfire Andromeda has a slightly lower impedance along with a slightly higher sensitivity, so the hiss might be a touch more noticeable through them.
Lastly, there’s the analogue volume knob which also feels like a quality piece of kit. It feels buttery smooth, and when I wiggle it around there really doesn’t feel like there is any amount of play in it. I suppose it would’ve perhaps been nice if the dial was a bit bigger, but there’s also only so much space it can take up on such a slim profile.
Over on the rear is where we find the stereo RCA inputs and outputs, as well as the input for the power adapter. The RCA jacks also feel very securely mounted and there’s practically no play in them. Unfortunately, the outputs on the back does not mean that the A50 can act as a preamp. In fact, when the amp is turned on, the RCA outputs get completely muted.
Whilst this will probably not be a deal-breaker for most people, I know many (myself included) would’ve liked to have a preamp function. I also would’ve appreciated an additional set of inputs as that would negate my need for a seperate switch between my PC and my turntable.
But yeah, as far as build quality goes, the A50 is fantastic, and whilst it might not have a longer list of features, I think considering the $169 price-tag it’s still perfectly acceptable.
Sound
Judging the sound of an amplifier can be a pretty difficult thing to do because an amplifier really shouldn’t sound like anything. It should just be taking the signal received from the DAC and amplifying it. In reality, however, amplifiers can alter the sound.
This may be due to a couple of things, including the effect that the output impedance has on the headphones, or perhaps the amplifier produces certain types of harmonic distortion. There certainly are some very in-depth measurements that can be performed, but unfortunately none of which I can conduct myself. I can’t tell you how accurate the specs are with regards to the THD or SNR figures, or what types of harmonic distortion it creates. If the D50s DAC is any indication to go by, however, I’m fairly confident that the A50 will measure really well considering just how well the D50s measures. Topping know what they are doing, and they are capable of engineering some seriously good equipment.
As for myself, the closest I can get is to doing measurements is a simple frequency response graph.
As we can see, the A50 remains almost perfectly flat from 20 to 20kHz. It’s only between about 60 and 20Hz that it rolls the bass off by about 0.8dB. Ideally we’d not like for it to rolloff anywhere at all, but such a relatively minor rolloff is not something that bothers me.
Whilst listening to the A50, it sounds exactly how I would want it to sound…as if it’s not even there.
When listening to binaural tracks such as those recorded and produced by Chesky Records, you really get a sense of the space in which everything was recorded and the separation between the left and right channels. Honestly, that’s all I can say before getting to the point of just kinda making stuff up to sound interesting. The cleanliness and transparency of this amp is fantastic, essentially what you’d expect not just from an amplifier in theory, but what you’d expect from a top-of-the-line product.
However, the A50 doesn’t cost what you’d expect a top-shelf product to cost, does it?
Value
And that’s where the exceptional value of the A50 comes in. Yes, it would’ve been nice if it had a few more features here and there, but taking into account the power it can deliver, the features it does have, and the great build quality, I honestly cannot see the vast majority of people ever really needing anything more than what the A50 can deliver. The $169 retail price really is extremely reasonable for what you get, but what’s more is that you can find the A50 as well as the D50s DAC and the P50 linear power supply every now and again on Drop.com at a very healthy discount. In fact if memory serves me you can get all 3 for a bit less than $500 in total, which is just ridiculously good value proposition. I’m not so sure if the P50 will really give you much of a benefit, but a A50 and D50s combo for under $400 is just too good to pass up.
So, if you are currently on the hunt for a nice compact headphone amp, then the A50 might just be exactly what you are looking for. I will be getting the D50s at some point in the near future to compliment this A50, so do keep a look out for a review on it.