Note: This article is based upon the TOPPING A90 amp review made by Joshua Valour on his YouTube channel and is printed here in partnership with Joshua Valour. The review was originally posted on November 23rd, 2020. Edits have been made for clarity.
Josh Valour had some spectacular things to say about the TOPPING A90 amplifier. Despite a minor complaint about the volume knob (see below), Josh calls this amp "probably the best amplifier on the market."
Watch the video below or scroll a bit farther for the lightly edited transcript.
Transcript of Video
Hey, what's up, guys. My name is Josh, and today I'm very excited to bring you probably the best amplifier on the market today when all things are considered: build quality, sound quality, specifications, measurements, and price. That's going to be the TOPPING A90. This features some of the latest and greatest of TOPPING’s tech, so let's go ahead and take a look at it and break it down in this review.
So I think right away—because some of the features that are on this and kind of the price category that it's coming in at—there's going to be a lot of questions about this versus the THX 789, so I'll be comparing a little bit against that.
Now the build quality of this device is actually very, very nice and it is a notable step up in terms of quality and feeling over something like [the] 789.
It's about the same approximate width and about the same approximate height, but it is not nearly as deep as the 789, and it's a little bit more shallow. That being said, it does feel quite dense and I think this is a combination of the internals and the chassis being what feels like a little bit thicker than that of the 789.
This also has some build features that I quite like, like the switches on the front which use toggle switches rather than buttons or dials, and I think they feel great, very analog, very crispy, very snappy-feeling.
Now, also on the front, you do have a volume dial and this is literally—and I mean literally—the only complaint I have about this amplifier in this entire review. The one complaint is that this dial is a little bit hard to turn because it's kind of shallow. The actual dial smoothness and resistance is phenomenal, but the actual size of it not being that far out it's a little bit hard to get your fingers around to turn, but that's the one and only complaint that I have here
Now, unlike many other TOPPING devices, this doesn't appear to have support for a remote, so no volume control via remote unlike a lot of other even lower end TOPPING devices. So a power cable and your warranty card is pretty much all you get in the box.
Now, on the back, it's fairly dense-looking, but it is pretty simple. You have XLR and RCA inputs and pre-outs. Your power cable input and then your power switch on the front. You have your gamut of switches, which is going to be your off/on and pre-out switch, your input RCA or XLR, and your low/medium/ and high switch.
Then you're also going to have your output for your headphones, which is going to be a four-pin XLR, 4.4 millimeter balanced, or your single-ended quarter inch output. And then of course the volume knob.
So the way that this goes about amplification internally is actually fairly unique for this price range and apparently has resulted in a very incredible amplifier for the money.
Now, what's awesome to see is that with that promise they also delivered on the specs, and this thing is a measurement-and-spec-beast. It’s absolutely a unit, so not only is this technically above pretty much everything else in the price range it actually competes directly and—I mean quite literally directly for measurements— with things like an HPA4, which is a three thousand dollar amplifier, considered to be among the best in the world, and this again competes directly with that for specs and measurements.
Now, for the power output, you'll see a slight edge over something like the 789 for pretty much the entire range. So at 600 ohms, this puts out 0.5 watts as opposed to the 0.4 watts of the 789. And you see similar slight spec beating in terms of power output than the 789 when you go to the single end of performance as well.
Now this does have one notable build benefit over that of the 789, and that's going to be the XLR outputs on the back. I'll talk more about that in the conclusion.
The total harmonic distortion is incredibly low. I think it's like 0.0000 six percent or something—just ridiculously low and the signal-noise ratio is like 145db. So this thing is incredibly quiet…very dynamic. It’s awesome. Now, if you're interested in more specs you can actually view a lot of them in Apos’ website in the description.
Okay so for sound quality…um: perfect. (Long pause) We could sit here all day. That’s it. Timing: great, decay: great, dynamics: great, tonality: excellent. Anything and everything, literally—I have not heard better for any particular thing unless you’re going to go with like…getting tubes or something, because you want the tube warmth. But as far as solid-state amplifiers go, this thing is a piece of glass. It’s transparent. It’s see-through. It doesn’t seem to influence the sound in any way, and it is just awesome. It’s kind of perfect. And I don’t mean to exaggerate here.
This thing literally doesn’t have any definable characteristics that can carry about from one headphone to another that I’ve been able to perceive on this. Now, the big audio no-no that you’re never supposed to admit that I’m happy to admit here: I think that this thing is far exceeding my capability as a listener, and I believe it will exceed most of yours as well. This thing really is truly incredible.
Now, I do want to talk about the sound here, because I don’t want to do a cop-out, but I want to explicitly state from this point forward when we’re talking about the sound, this is going to be like the “placebo area,” where things are so minor, and getting into that area of being really potentially the cause of a slight volume difference or just the day of the week or whatever it happens to be between this and a couple of amps that I’m going to be talking about.
As far as testing equipment, we’ll talk about full-size first. We have the Arya, the Abyss Diana Phi, and the Abyss Diana V2. And off-screen I’ve got a couple other dynamics over there that I was listening to as well.
I do want to talk a little bit about the THX stuff more directly. Okay, so compared to the THX style of amplification, there’s something about the way that these two amps handle sharpening or edges that seems different. The THX amps always feel a little bit sharp. They feel exacting. They feel super-precise. They’re still extremely transparent and probably as transparent as this, but if they were to have one defining characteristic of the sound that carries over from headphone to headphone, from DAC to DAC, no matter what you’re listening to—the sound always has that really clinical, uber-precise nature to it. And to be honest, most of the time I actually think this is a great benefit and sounds very good on most things, unless it happens to be an overly-clinical and overly-sharp headphone by itself, which none [of these headphones are]. These are more on the upper-end of detail-retrieval but not necessarily sharpness. Something like sharpness would [define] a DT1990 or something, but with the THX stuff you get that introduction of the sharpness in everything you listen to.
So you can take a relatively calm headphone in the detail-end and put it on a THX, and it’s going to sound more detailed than it will on a lot of other amplifiers. Now, this is where the nuance comes in here, because the A90 feels clearly just as detailed—like, no questions asked, definitely—but it doesn’t have the added sharpening feature or factor to the sound that the THX amps have. And this is a very minor difference. It almost is like the edge of any given point of sound—like if we were to just pause sound and look at it, a lot of sound would have edges on THX stuff, and on [the A90], it just seems slightly rounded. And we’ve all seem those super-generic graphs about DACs where they’re showing like, “oh we’re changing like the bits to be smoother,” you know, all that fun stuff. It’s sort of like that, but not quite to the extremes that a lot of the marketing would lead you to believe. But honestly, my perspective on [the A90] is that this is just as detailed [as the 789] but a little bit more natural. But it’s very, very minor. Now that goes for almost all of the current THX amps that I’ve heard, not just the 789.
But something that is specific to the [TOPPING A90] is the spaciousness. And this is, again, minor, but it was a difference that I believe that I did perceive was especially on the Dianas. The spaciousness of sound felt more transparent and see-through but maintained all the quality and saturation, but it just felt a little bit more open and further-out on the far ranges of music than the DAC/amp did. Now, again, [this] could be the placebo [effect], [or it] could be a slight volume difference [or it] could just be how the voltage is handled different or the power different between the two. I’m not sure, but that’s what I took to be the difference between these when I was listening to this.
Now, all that’s well and good. I think on most headphones, you’re working with a relatively equal playing field for the top end of amps…and I think it all, for the most part, really sounds the same for the core and the majority of headphones…But where the [A90] is different, and the defining moment and feature of the [A90] that I think separates it from those other things is the IEM performance.
The fact that the noise floor is completely dead on every IEM I try, on low gain, on this is a total victory. It absolutely solidifies this as the best amp. See, I’ve got this problem. The problem is these headphones right here, which are M5s, which, similar to the Empire Ears Odin here, feature a number of different drivers: a dynamic driver, a balanced armature, and an electrostatic. And that electrostatic driver is particularly sensitive—very sensitive—more sensitive than even the electrostatic in the Odin. And this IEM—I shit you not—on every full-size headphone amplifier that I’ve tried up until this point has had a notable noise floor.
Now, it wasn’t a big enough deal to not use an amplifier on this IEM, because once you’re playing music it’s usually inaudible, but I don’t have to make any compromises with [the A90] amplifier. Now, the reason why this is so important to be is because [the A90] works—what I consider to be—perfectly for every range of headphones, from IEMs—extremely sensitive ones—to the most demanding planars on the market right now. This amp has got everything covered. All of it.
Now, for IEMS, there are other features that are very important that not all amplifiers play well with. A big one for me is dynamics. A lot of the more powerful headphone amplifiers have real issues with dynamic control of IEMs. They don’t have the nuance that I think is required for really sensitive IEMs. So what you’ll see is, you’ll plug the Moondrops or the Odin or the M5 into a 789, and you’ll get this kind of jumpy sound where it feels like it’s just ready to be released, and it’s got a lot of pent-up energy, and you can hear it in the dynamics, where things are very spiky, and they’re kind of jumping up at you. The [A90] have it. As much control and nuance as it has for those large planars, it has for IEMs. And the dynamic range is proper. It’s where it should be. And it has the subtlety and control that it needs for IEMs. I’m making a big deal out of this because I think it is a big deal. This is very hard to do because almost no other amplifiers that are made for the types of headphones that this is made fore have the benefits of being able to run IEMs as well as this does. So it is a big deal.
So my conclusion to this. This is the best test bench amplifier that I’ve run across so far. [It’s] the best kind of all-rounder that can do everything and is great for all of it. Now, depending on your perspective on things—and where you’re coming from, what other amplifiers you’ve owned—this is either one of two things. This is either an expensive THX 789 that features a little bit better specs and better features or it’s a six times cheaper HPA4. And I think the answer is that it is both of those things. It is a little bit better than that of the 789, and it has comparable performance at six times cheaper than that of the HPA4.
Okay, now, while I think that this is—within the limitations—probably the best amp that you can buy right now, that doesn’t mean that it’s going to be the best for everybody. I think if you’re looking for what this offers, it is the best. Like, if you’re looking for ultra-clean, ultra-good specs, good functionality, wide versatility of use-case, this is it.
But if you need other things, like maybe Bluetooth or an all-in-one DAC/amp, or x, y, and z features—things like that—there are still going to be other amps on the market that are probably going to be better for you.
Before I go, I do want to bring up one last feature or mention that might be a deciding factor for some. So this thing—over the THX 789—does have XLR pre-outs at the back, which means that sound engineers should actually give this a legitimate consideration for a sort of amp or volume control for powered studio monitors, because it does have that XLR, and the XLR output features the same incredible specs as the headphone output does, so this is an ultra-clean, well-measuring, fantastic interface for both powered studio monitors and headphones. And you can just switch between the two. I think that’s a legitimate use-case and benefit to specific people over something like the 789.
Thank you very much for watching. I want to thank Apos again, and you’ll find links again in the description down below. And until the next video, my Name is Josh. Signing off. Bye.
End of transcript
Editor's note: Emphases ours.