ALO Continental V2 headphone amplifier in review

I have high blood pressure. I get excited easily. For my weight and height, I have a large bum. Fortunately, after applying minus 6 and minus 5 contacts to my eyes, my vision is good – I can tell a masterpiece when I see it. I’m certainly not one. The ALO National is. But for the mistake of ending early, so is its forebear: the Continental V1 nearly is, too. The Continental V2 makes the grade, too. It shares most of The National’s good stuff and brings to the table a sound all its own.

Dimensions: 2.32 x 3.89 x 0.56
Battery Play Time: 7-8 hours
Battery Recharge Time: 3 hours
Frequency Response : +/- 1 dB:40Hz-20KHz
Input Impedance: 30KOhms
Maximum Input Level: 5VRMS
Channel Tracking: < +/- 0.2dB
Maximum Output: 20 V Peak to Peak
THD+N: 1%

Contact ALO
1810 SE 10th Ave. Unit B
Portland, OR 97214
Phone: +1 (971) 279-4357

This review is TMA’s third glut of grammatical errors and mug shots dedicated to valve amps. The first detailed Woo Audio’s WA3, and gushed on and on about craftsmanship and a sound that is decidedly ‘tubey’. The second, detailed the GoVibe Porta Tube+, and waxed lyrical on about beautiful highs, buttery smooth transitions, but waxed cynical about its itchy workmanship.

The Continental V2 is every bit the feat of engineering that the Woo Audio WA3 is, though it runs from batteries, not the mains. Its guts, rather than being strung point-point, lay soldered into silicon. It is solid, beautiful, ergonomic, and a pleasure to use in every turn of its volume pot, in every flip of its volume lever.

And, most important of all, its voice effuses the same lush, rich midrange, the same delicate highs. Woohoo!

Build Quality
Because The National and the Continental V2 are – practically and wonderfully constructed – two peas in a pod, I’m tempted to copy and paste test from The National review here for reference.

There is very little that distinguishes one from another in quality of build. The Continental V2 inherits every one of The National’s good points.

On the outside, the differences are nill. For the sake of brevity, you can read my gushings here. For the sake of thoroughness, however, the differences, where evident, will go down here.

The most obvious comes in fifteen tiny holes sunk into the amps’ brow and temple, just above the valve. These help ventilate hot air coming from the valve. The Continental V2’s guts sit in a smaller chassis than Porta Tube+ guts do, and are sewn in tightly. They need all the ventilation they can get as the Continental V2 gets quite warm.

One reason the guts are sewn in so tightly is that ALO followed Apple’s lead and have glued the battery into the V2’s chassis. Thus, the battery isn’t user replaceable. If by chance the battery should perish, ALO will replace it for you. But you, armed even with the most ferocious of spatulas and pick axes, will not get it out yourself without damaging the spatula, and perhaps the pick axe. The Continental will be reduced to a resume of interesting parts and aluminium shavings. You won’t be able to check the circuit board, either, without breaking the seal. The Continental’s guts, my friends, are tucked safely (and very securly) into their skeleton.

Apart from that, both The National and the Continental V2 share the same thick, scratch-resistant aluminium chassis and are built to the highest standards possible.

Ergonomics and Polish
Again, I’m tempted to copy and paste my ramblings from The National review. Instead, I’ll let you read it on your own.

Overall, nothing drastic has changed. The same perfect spacing, wonderful volume pot, easy-to-engage gain, the same perfectly lit lamp – all there. The Continental V2 is all that The National is, and a bit more. Bigger that is. It’s about 1 centimetre longer front to back. But for a bit of paint advertising ALO’s website, the front and back plates are virtually identical, too.

The difference – and my wife feels this is no small thing (and it isn’t – it’s huge) – is the brand font. Yes, folks, I’m going to yammer on about a font… in an amp review.

I’m with my wife here and much prefer The National’s tastefully off-centre, newspaperesque script. It’s less geeky, more metro, and utterly attractive. The Contintenal’s font is classy, but it’s the Masonic ALO badge that has me hiding the entire amp in an Apple Sock.


That’s just my interpretation of polish.

Let’s get back to ergonomics. Like I said, there’s not much between the two amps. They’re siblings through and through. Hot siblings. The National dissipates quite a bit of heat for a solid state headphone amp. The Continental V2 dissipates quite a bit more. So much more in fact, that I can’t recommend stuffing it in your pocket in a Japanese summer.

I did that on my way sweaty way to immigration.

Damn near electrocuted myself.

Again, nothing new here. Both the National and Continental are straightforward amps. Plug in your source, your phones, adjust the gain, the volume, and enjoy. And, assuming you enjoy rich, lush sound, you will enjoy.

Under the bonnet is the Continental’s magic, a tiny, low-voltage valve and a sound that fits the description. The volume pot is wonderfully balanced, and its low gain setting fits most highly sensitive earphones just fine.

Here, I’m not tempted to copy and paste. The sonic differences between the National and Continental are evident from the first listen. Still, I think you will agree with me that ALO have begun to develop what I think is a nice house sound, though between The National, Continental, and Rx brands, there are important differences.

Valves amps take time to wake up – and sleep. Portable amps are no different. The Porta Tube+ goes from silence to full sound in about ten seconds. The Continental takes about 12-15 seconds longer. Turn it off, and music drifts out in the same manner. It’s like pins and needles, but much more fun.

Then, there is power. Both amps spit out enough voltage to get almost any headphone to ear-splitting levels, though their approach is different.

With headphones and earphones that present small loads, say over 40Ω, the Continental will give quite a bit of extra low end rumble. With no load, that peak, which starts pretty much at 20Hz and goes to about 120Hz, is even bigger. It’s very interesting, and for people that consider cans like the DT880, K701, and K550 to be bass shy, this low end hump could be a godsend. Also interesting is the placement of this small, but discernible hump. It isn’t in the mid-bass (the frequency slot that most people call bass). No, it’s in the proper bass.

This amp raises that frequency band by up to three decibels. But even if ALO were to have raised it by 8 or so decibels, they would still have obviated boom and bloom that occurs from raising the mid bass. Just a reminder: extreme frequencies tend to border on inaudibility. But, this hump is discernible – if your music has that information to begin with, and if your headphones aren’t severely rolled-off to begin with – though just.

Interestingly enough, that same bass (sub-bass to help the younger generation) isn’t held up when using headphones of less than 40Ω. The amp becomes a different beast with low Ω headphones. Most presence is shifted to the high-mids. Both bass and high treble dynamic presentation is softened.

Which I am fine with. Here’s why:

Though the Continental II is a portable amp, it is probably best suited to desktop-replacement work, where it will drive highΩ headphones that value its voltage.

And regarding size, the Continental II is just longer than The National, weighing just a bit more. But as I said before, it gets warm – quite warm. The National lit a small fire in the pocket. The Continental should probably stay out of the pocket to begin with! It does get warm. The breathing holes are there for a reason. Keep them clear. In my month or so of use, I’ve found that I tend to use it most near my computer, or on my sofa almost always plugged into my DT880 600Ω which is basically made for it.

Besides the above-mentioned bass bump, the Continental II has that telltale valve sound – warmish, with a dry (like wine, not humour) lower midrange. On a valve scale, it is more Woo Audio 3 than Porta Tube+. In fact, the differences between Jaben’s and ALO’s amps are stark. Jaben’s amp is loved for its extended but smooth high range, while the Continental is loved for its well-resolved midrange, warmth, and slightly elevated bass. Both are valve amps, but in sound signature, the two are very different.

Their similarities are the similarities that nearly all valve amps have: high distortion. That distortion smooths out little niggles in bad recordings, and tames some screechy headphones. Smooth really is the name of the game. In Japan, both amps have drawn comparisons, and some people have decided there isn’t enough difference to make a decision, while others prefer one or the other for a certain reason.

The Continental outputs a tad less background hiss than the Porta Tube+ and sports the necessary (as this amp is powerful) gain switch on the outside of the amp. Jaben requires you to undo the front plate, get out your eyebrow tweezers and replace jumpers.

I find the Continental II to be clearer in the bass while the Porta Tube+ is clearer in the upper mids (hence, maybe, the reason I fell in love with its high mids). They are similarly congested in the highs, but again, that congestion is comfortable. Overall, for a warm tubey sound, the Continental II is a better buy. For a slightly clearer, but more solid state sound, the Porta Tube+ is better. Other decisions should be made on the headphones you want to use, and on build quality.

Remember, the Continental is more at home with full size headphones and portable phones with impedances of more than 40Ω. The Porta Tube+ is equally comfortable with low or high Ω loads.

Sound in a Nutshell
Smooth out The National’s highs and upper mids a bit, add an emphasis to extreme lows, and some of that good ol’ valve distortion and you have the Continental II. There really is a family resemblance to the two. It is amazing. The Continental II also has less background noise, but with low Ω headphones and earphones, it is also less dynamic. If you are primarily using earphones, I suggest staying with The National, which will give you harder hitting lows and a more exciting upper midrange.

But, if you are out for the warm, lush valve sound and use headphones of more than 40Ω, I can’t recommend the Continental II enough. It really is the most characteristically tubey amp I’ve heard. Ever. Woo Audio 3 in your pocket. Tell that to your friends.

RMAA scores
For those interested in seeing RMAA scores, go here.

Scaling with better sources
As with most good amplifiers, you will get more power from this amp with higher quality/more powerful input. The CLAS is a source that will really up the output power. Fortunately, the volume pot behaves well even when hooked up to line-level sources. With full-size headphones, it is perfectly matched with a good HiFi or CD player.

In fact, I recently attached a Hifiman HE5 to the Continental II and was surprised by the power and control in the combination. Again, I listen to lower volumes and have no intention of bursting my eardrums for reviews. I listen to enjoy my music, not break my biology.

Best headphones for the Continental II
As long as you have a somewhat sensitive headphone, even 600Ω is chicken pie. The DT880 600Ω goes with high gain to about 88% of the volume scale with no phase errors or other telltale signs of distortion.

My Audio Technica ES10 is also another wonderful combo headphone that fits the Continental’s nature. I have a feeling that if you find your headphone to be ‘sibilant’ or harsh, the Continental may well be the amp for you. I’ve heard it said that even warm headphones such as the Sennheiser HD60 ( shares good synergy with this amp.

My only issue with the Continental II is that it doesn’t play nice with low Ω earphones. It’s definitely audible. The amp has wonderful bass and wonderful highs, but with low Ω earphones, you will get an upper-mid centric amp that isn’t excessively detailed. The output impedance seems too high. Plug in a pair of ES7 headphones to it and the National, both matched to the same out line volume and the ES7 is quieter and less dynamic on the Continental II.

Which is a shame because otherwise, this amp is the sliced bread among portable valve amps.

What’s the conclusion?
Let’s face it, ALO are one of the masters of portable headphone amplifiers. Not a one lacks sufficient power, nor good looks, nor build quality. And as I said above, there is a definite house sound developing, and overall, that sound is great. The Continental II has a very low noise floor, excellent ergonomics and build, good low end kick, and great balance. If it were not for the fact that low Ω earphones sound congested in comparison to proper headphones – this is, after all, a portable amplifier – I would consider this the king among ALO’s amp line. Mated with the DT880 (250 or 600), the T1, T70, HD600, K701/2, K550, etc., it is one of the most soothing, beautiful sounding portable amps out there. With 7-8 hours of battery life, you can forgo the mains for your home rig, and pack in an entire day (or night) of music loving. For headphone users, I consider it a must-have amp. Fit it in your bedside rig, your HiFi, your TV rig – anything. Because it really can sing.

Like a WA3 in your pocket
Warm, smooth sound
Extra low end for high Ω headphones
Excellent ergonomics
Excellent build quality

Gets hot
Low Ω earphones change the sound of this amp

Hot damn! Headphones really are a rockin’ way to enjoy music, right? Feel free to explore TMA’s headphone oubliette

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