XI Audio Broadway S

XI Audio Broadway S is a really interesting transportable headphone amplifier that is battery powered and it runs a pure analog discrete class A. It is priced at $1599.
Price Power supply Impedance Amplifier
$1599
Battery
800mW / 16Ω
Class-A

Introduction

XI Audio is still a relatively young company, which is often seen in the company of American Abyss. Their flagship headphone amplifier, the Formula S is commonly regarded as the best headphone amplifier pairing with the 1266, and one of the best amplifiers in the market generally.

But it’s not just the Formula S, they also have their widely praised Sagra DAC using R2R technology, and two Broadway amplifiers. Today we’re gonna review the most affordable and less powerful of the two – the Broadway S. Sit down and enjoy!

Packaging

So, long story short – I didn’t get the original packaging with the Broadway S. It was sent to me as a review sample by XIAudio and it came in a plain white box, hence I can’t really say anything interesting in this paragraph. 

Of course, the amplifier is not the only thing that you’ll be getting. XIAudio also includes a power supply that also works as a charger and a screwdriver. I’m not sure if there’s anything more included with the retail packaging. At the end of the day – it’s an amplifier, so you won’t even be expecting anything extra, to begin with. Let’s move on.

Design and Build

Now, let’s move into a more interesting topic – the actual design and build quality of the unit. The Broadway S is built really well – it’s solid, dense, and kinda minimalistic. Having in mind that it is a battery-powered, pure analog discrete class-A amplifier really makes me impressed by the overall size of the unit itself, which is small and handy. 

The whole amplifier is made of metal, and there’s simply nothing to be worried about regarding the build quality. It’s made to last.

One of the most important things regarding the build quality of the headphone amplifier is the volume knob, as it’s often the only physical thing that you’ll be regularly touching. So, how’s the knob in the Broadway S you’d probably ask? Well…it is absolutely brilliant. Buttery smooth, big enough to grab comfortably, and an overall joy to use. What’s interesting though, is that the starting point of the volume knob is located at 11’o clock, which is marked with a XI logo – a nice touch indeed. 

Other than that, I definitely got 1 complaint regarding the physical aspect of the amplifier. To turn it on, you have to click the switch that is located at the back panel, and that’s really problematic for me. See, as a reviewer, I usually tend to have a lot of different devices on my desk, so even though I have a 2.5m long desk I need to stack things. Here comes the trouble – the power switch is very, very uncomfortable for me to access, so I usually have to disassemble the whole “amplifier mountain” just to power on the Broadway S. 
Of course, it’s not a deal-breaker, it’s not even close. But I’d highly recommend XIAudio to put the power switch on the front panel, or at least a kind of standby button.

Nonetheless, there’s nothing to really complain about. On the front panel, all you’ve got (except the volume knob) are two headphone outputs: A 4-pin XLR and a 6.3mm jack. Keep in mind that the XLR output is single-ended only, as the Broadway S is not a balanced topology amplifier. It’s there for convenience really, as many of you probably own a balanced cable anyway. 

As far as the design goes, the Broadway S surely looks like something that is meant to sit on a desk of a studio engineer. It’s classy, pro-looking, and kind of raw with its presence, which definitely looks good. It has that industrial vibe to it that screams “pro”, and it works wonderfully. 
The last thing worth noticing is the feet. I’ve seen some early units that had a 3-leg design, which caused the amplifier to be quite problematic to use. Luckily I can report that it’s now using 4 legs just like the majority of amplifiers on the market, and it sits on the desk like a champ. Hear the feedback and adjust – that’s the way to go.

Tech

Imagine that you’re going to the manufacturer’s website, you choose the Broadway S, and the first sentence is as follows: “The world’s first high-performance Li-Ion battery discrete class-A headphone amplifier”. That’s a pretty exciting start, isn’t it?

So, let’s start with the beginning, and probably with the most impressive thing. The Broadway S is battery-powered, which you can charge with the included power supply. But wait, there’s one important thing…it doesn’t use some standard battery, but 4 18650 batteries. What does that mean? Yes, you guessed that…battery rolling! 

I’m not even kidding, I’ve spoken with XIAudio and they did confirm that changing the batteries for a different brand indeed changes the sound a bit. That’s absolutely brilliant because you’ve been granted with almost endless possibilities to upgrade/change your amplifier without spending more than 100$. Another important thing is that it works for up to 11h on a single charge, which is really impressive for a 800mW/16 pure class A amplifier. 

Speaking of the power, 800mW into 16 Ohms is not much for today’s standards, but it definitely has its aces up its sleeves, more about it later on. On the bottom, you’ll find a gain switch, but you probably won’t ever have to use it. That’s because even on high gain, the Broadway S is so absurdly clean and silent that only the most extremely efficient IEMs might give you any hiss out of this amp. Even then, I’d prefer a better headroom and more dynamic presentation I’m getting out of the high gain setting. 

Sound

Let’s get into the sound. Right from the start, I have to state one thing – forget about running your Susvara, 1266, HE-6, and other super high-demanding headphones out of the Broadway S. It is simply not meant for them since its output power isn’t high. What’s it just perfect for though are IEMs and not really demanding headphones like the new Arya SE, HE1000se, LCD-X 2021, and so on. And boy oh boy, this is absolutely magnificent with them. 

 

The bass is fast, well-controlled, rich, and very dynamic, it sounds reminiscent of a good Class-A amplifier, which it is. It has a very solid punch to it, and thanks to its cleanliness and top-notch resolution you’re gonna get all the textures and details that should be present in the recording. The Broadway S is clearly a clean beast, and it gives all the perks of an extremely clean, low-distortion amplification. What’s worth mentioning, is that the Broadway S won’t change a lean-sounding pair of headphones into bass monsters. It is more of a chameleon that ensures the very high-quality signal goes into your headphones than it is altering the bass signature. That’s exactly what a good amplifier should be doing.

The midrange is the star of the show here. It’s natural, fluid, lush, and superbly clean, which give you one of the best vocal performances you’ll get in this kind of amplifiers (not powerful ones). The overall sound throughout the whole mid section is highly saturated, airy, and crisp, without being even close to sounding dry or harsh. This is pure gold, very pleasant, and not overdone in any way. Thanks to that, it handles natural instruments and human voices exceptionally, no matter the headphone that you’ll be using. 
In my opinion, it sits in a dead center of how the midrange should be tuned in audio. Lush and rich enough so it sounds extremely natural and pleasing, yet very clean and detailed with excellent resolution so you’re gonna hear every single small detail in the recording, whether you’re supposed to or not. Absolutely brilliant.

Let’s get into the treble. No more delicacy and lushness, the high frequencies are handled like a sports car – they are forward, detailed, clean, and crisp. You’re getting a flawless reproduction of details throughout the whole spectrum with the Broadway S, but it is the treble that shines the brightest in this regard. There’s a certain characteristic thing about a good Class-A treble reproduction, and it is definitely present here in this amplifier. It is the sensation of a highly detailed and flashy treble response, that is quite thick and saturated at the same time. When you’re listening to some good metal recordings, you want the cymbals to have that rich, metallic (but not harsh!) tone to them, and the Broadway S will give you exactly that. It is not a lean-sounding amplifier in any frequency, but especially in the treble. Notes have a proper weight to them, which further empowers the feeling of listening to a live performance. 

Thanks to the overall tuning and a brilliant technical performance of the Broadway S, the soundstage is just a joy to listen to. When paired with a good staging pair of headphones, like the 1000se for example, you’re getting a pin-point accuracy, perfect separation, and a lot of air between the instruments, without making the soundstage unnaturally big. This little guy will give you exactly what’s been recorded, so the soundstage characteristics will mainly depend on your headphone of choice. 
One thing that is sure is that the imaging and separation are top-notch, so I would definitely pair it with an excellent-staging headphones or IEMs. 

There’s not really much more to say, it is a clean, natural-sounding amplifier with brilliant technical capabilities. I decided that I’ll go deeper in the pairing section of the review, as it’ll give you a better idea of the actual performance when paired with some popular picks. 

Pairings

 

Hifiman HE1000se

Let’s start with a bang – the Broadway S is the best amplifier I tested with the Hifiman HE1000se SO FAR. This headphone doesn’t require basically any power to be driven properly, but thanks to its world-class technical performance, they surely need a very clean and natural sounding amplifier. So, let’s dive a little deeper.

The 1000se basically has a top-tier bass response, both in terms of detail reproduction and texture and control. They do require an amplifier that’ll do the same, and the Broadway S delivers. The bass of this pairing is strong, impactful, and powerful, but at the same time well-controlled and it reaches all the way to the bottom. What’s even more impressive, is that even though low frequencies are quite big, they never interfere with the midrange in the slightest, and that’s definitely what you’ll want in such an expensive setup.
The midrange is the reason why the Broadway S is the best amp that I’ve tested with the 1000se yet. Thanks to its smooth and very natural presentation, the 1000se starts to truly sing. This headphone tends to get a little hot with some pairings in the upper-midrange region, and it’s not present at all with the Broadway S. All you’re left with is a beautiful, emotional, and top-notch technical midrange presentation.
The treble is the region that might be interesting here, as both the Broadway S and the 1000se are energetic and highly forward sounding. There’s a certain thing to both though, that makes it a great pairing – the resolution. While the treble sounds very saturated and shimmering, the masterclass resolution of this combo holds it together in a very delightful way. Sure, it is a treble-forward sound, not even close to being called laid-back or delicate, but you won’t be getting any harshness or brightness. 

Audeze LCD-X 2021

 

The Audeze LCD-X 2021 is a perfect pair of headphones for the Broadway S. It doesn’t need much power, and its sound signature is a perfect match. While the Broadway S is superbly clean sounding with a forward-sounding treble, the LCD-X 2021 is a rather intimate and thick-sounding headphone that definitely might use some treble energy. 
It all translates into a very pleasant and very detailed sound coming out of this pairing. The amount of energy throughout the whole frequency range is spectacular, the vocals are yet again addictively lush and sweet, and the treble is just right when it comes to its extension and texture. The song “Abraham” by Miles Mosley sound simply spectacular, with that very forward and pleasant sounding voice of Miles and the bass vibrating and giving that constant tempo. You can hear the size of the bass in the left channel, it is big and impressive, while all of the remaining sounds are perfectly clear and separated. 

Overall, this pairing thrives with rock music, especially records from the ’70s and the ’80s. It’s analog-sounding, rich and flavorful, yet highly engaging and very detailed, without going to extremes. Everything from Fleetwood Mac, Foreigner, Marillion, and Black Sabbath sounds really great, not overwhelming, and highly musical. It’s quite forgiving for poor masterings, not because the lack of details or any problems with resolution, but thanks to its rich and thick tone. 

Final D8000 Pro
 

Now, this is VERY interesting. Does the Broadway S have enough juice to unleash the full potential of the D8000 Pro? Not really. Damn, it won’t even go very loud until the sound starts to sound really weird. But if you’re listening at reasonable levels (still quite loud), then this combo is absolutely mesmerizing. It sounds vastly romantic, intimidating, ridiculous. 
The bass is loosen up a bit, and it works like a charm here, presenting the low frequencies in a fun way, with a lot of subsonic rumble. Don’t expect a very high level of tightness or a perfect control, as you won’t find those here. Nonetheless, it’s very punchy, vivid, and fun to listen to.
The midrange is…damn. Listening to Lunatic Soul – A Thousand Shards of Heaven literally gives me goosebumps. First, the vocal is forward, airy, and very, very euphonic, almost vibrating. It’s a very strange sensation that I’m absolutely loving, it makes that warm and delicate voice of Mariusz Duda sound like I’ve never heard before, and I’ve tested that song on hundreds, if not thousands audio systems in my life, and some of them were $100k+. 
And now onto the main point, the soundstage. The D8000 Pro is a good staging headphone, but not class-leading in any way I’d say. That was my impression until I plugged them into the Broadway S. The width, depth, and imaging are absolutely staggering, one of the most impressive I’ve heard to date. 

That combo is a great example of a pairing that is definitely not perfect, but it simply does wonders in many areas. While the dynamics are limited and it can sound a little big flimsy from time to time, because of the D8000 Pro being slightly underpowered, it offers a very euphonic and romantic sound that is addictive. And I mean it, I’m listening to it literally right now. 

Fir Audio M5

Let’s talk about an IEM pairing as well. I’ve chosen my custom Fir M5, as its top-tier resolution is a good match for the Broadway S. First thing that surprised me was the soundstage – it got absolutely massive, in every direction. What’s pretty interesting is that the vocals took a good step back, just like every other instrument in the mix. This gives a very spacious and vast presentation, with a brilliant resolution throughout the entire frequency range.

I’m not a big fan of pairing IEMs with such amplifiers, as all they really need is a good quality DAP, but I can hear why some people might prefer it. The overall sound is massive, the M5 really sounds like an open-back headphone, a spacious one to be precise. 
Random Access Memories by Daft Punk is a great show with this pairing, offering a very dynamic, big and extremely wide, and deep presentation that’s pretty easy to fall in love with. While I still mainly use my IEMs with DAPs, this pairing gives me a more spectacular and punchy sound presentation that I find myself craving for quite often lately. 

Summary

The XIAudio Broadway S is a very interesting and extremely technical battery-powered amplifier. It has a romantic soul with its spectacular midrange presentation, and its soundstage is among the absolute best I’ve ever heard. Add a superb detail retrieval and top-tier resolution to the equation, and you’ll be presented with a true pinnacle of transportable amplifiers, that is not only technically impressive but lovely to listen to.

Highly recommended.

Gear used during this review for the sake of comparison and as an accompanying equipment:

  • Headphones – Hifiman Susvara, Final D8000 Pro, Audeze LCD-X 2021, Hifiman Arya SE, Hifiman HE1000se, Fir Audio M5, Unique Melody MEST, Campfire Audio Solaris 2020
  • Sources– Topping D90se, SMSL SU-9, LittleDot MK III SE, SMSL SH-9, Cayin N3Pro, Accuphase DP-570