Introduction
A bit of preamble - I bought this C5 amp to go with my FiiO X5ii and Fidue A73 set up. The idea was to get the amp to reduce the noise floor and offer a bass toggle for when I felt I needed it. I wasn’t expecting (or needing) much of an improvement in sound quality or sound signature.
 
I'd asked for advice on Head Fi forums, but had no responses. I’ve since be told you need be extremely specific in your requests, or post something interesting!
 
So I based my purchase purely on trusted Internet reviews on Headphonia and Inner Ear, and based somewhat on availability. For the record, my shortlist was:
 
·      FiiO E12K Mont Blanc IEM special edition
·      Cayin C5
·      Aune B1
·      JDS Labs C5
 
What I really wanted was a ALO RX, but simply couldn’t afford. So out of my shortlist, the Cayin and Aune are/were not available in the UK, and I didn’t like the delivery options / costs open to me from overseas resellers. The FiiO seemed like the obvious choice, but despite UK companies having stock, it turned out the FiiO would come after the JDS Labs would from the US. So I opted for the JDS Labs for something a little different.
 
Buying it - 10/10
So the first issue was buying the C5. Unfortunately, there appears to be no UK resellers for JDS (if they are, they’ve switched on “discourage search engines” in their preferences! There was one on Amazon, but it simply states "Currently Unavailable", with no availability date or anything – really helpful, that.
 
So a direct purchase from JDS Labs' US store was necessary. I've had mixed fortunes buying online from overseas, but as JDS Labs is a reputable company using US Postal (the only thing they got wrong was Lance Armstrong!) and the delivery was insured, I wasn't concerned. I placed the order on the 23rd December, it was dispatched on the 24th (Christmas Eve, folks!) and a week later a well-packaged little amplifier dropped through my letterbox. A week is nothing but shipping standards - I ordered something from Currys PC World, the UK's equivalent of Circuit City, and it took 2 weeks to get to me (perhaps I was being taught a lesson as there is a store a 20 minute walk from my office). Still - a week at the busiest time of the year for an amp to come from the USA to the UK is excellent. Well done, JDS Labs and US Postal - you're already better than Currys PC World and DPD in the UK!
 
Packaging - 5/10
Inside the well-padded outer carton was the JDS Labs box. Now, having owned products from Apple, Samsung, HTC, FiiO, Rock Jaw and Motorola, I'm used to seeing good packaging. JDS Labs certainly haven't invested heavily here - a fluted cardboard box with bubblewrap inside does a good job of protecting the amp but does little for customer experience. Let's call it utilitarian. It works, but nothing more.
 
Design - 10/10
Once out of it's utilitarian packaging, it's clear where JDS Labs have invested. This is a beautiful product to look at and hold. I'll be honest, I'm not a fan of red. However, my Fidue A73 IEMs are red and grey, my FiiO X5ii is silver with a grey and red GUI, so I thought it would be a nice match – and I was right. But more importantly, the main body of the C5 is a lush red colour with a slightly coarse, matt finish that just exudes quality. The end caps are machined silver, which finish the product off nicely. That, coupled with the switchgear, this looks like a piece of high-end audiophile equipment rather than a polished consumer electronics product, say like the FiiO X5ii. Stunning, but only if you want that sort of thing. Personally, I love it.
 
Volume is a digital, but is controlled using a switch rather than a pot. It took a little getting used to, but works as well as the up/down volume buttons on the FiiO X5ii. Press it once in either direction and the volume goes up or down a step. Press and hold in a direction and it continues. I’d prefer a volume pot myself, but that’s just me and a very, very minor gripe.
 
Speaking of volume, I can’t hear any channel imbalance at lower volumes, although someone with better ears than me might. I do find it odd that the lowest volume is pretty audible and then the next setting down is off, not that anyone would want to listen lower than this volume I guess.
 
The on/off button and bass are lovely feeling toggle switches, and have a nice reassuring click to them. The charging port is the older style mini USB, not like the micro USB found in non-Apple phones and DAPs. This isn’t a huge issue, but it does mean if you’re travelling you’ll need to pack the mini USB as well as your phone/DAP charger. Everything feels really well built and solid though. I like it a lot.
 
Gain
There’s no gain switch. It’s MOSFET controlled. So there’s not a lot to report as I’m not an engineer, and the only listening devices I have are my ears.
 
Initial Sound Impressions - 5/10
When I first plugged everything in, there was a noticeably warm sound that the FiiO X5ii alone doesn't provide. However, everything seemed way too laid back. The detailing from the X5ii seemed to be swallowed up - everything was way too smooth and laid back. The vocals sounded behind the instruments, and I didn't like it at all. I was enjoying the music more from the FiiO X5ii without the amp more than with. It just sounded, well, wrong. But I persevered after reading about the amp's burn in time. 50 hours they said. So I waited. And waited. And waited.
 
And gradually, over time, the C5 went from "meh" to "marvelous".
 
Before I go on - a note about burn in. There are those that don't believe in it. Well, sorry but you're wrong. Maybe not every piece of equipment needs it, but some do. This amp's sound signature changed massively over time and definitely favours burn in. So there. Don't argue.
 
Burned In Sound Impressions - 9.5/10
Wow. My set up went from me preferring the sound of the built in X5ii amp over the C5 to no competition at all. The C5 though slowly grew into itself and began presenting a warm but wide, detailed and expansive sound signature that put all my music in a completely differently place. I have a list of songs I always use to test equipment out (http://www.head-fi.org/t/108584/the-best-audiophile-tracks-to-test-equipment/165#post_11519180) and I went through these songs to see how the C5 behaved.
 
I listen to a wide gamut of music, and it’s therefore very difficult to find equipment that isn’t too genre specific. The C5 seems to handle most genres well – but particularly acoustic singer / songwriter stuff like Ed Sheeran, George Ezra, Jamie Lawson et all. It’s warm, smooth playback brings a gorgeous texture to male vocals and separates them from the other mid frequencies beautifully. All this isn’t at the expense of treble or bass though. There is incredibly telling detail to be had from the C5, especially with my Fidue’s balanced armature design – although sometimes sibilance can be a factor (but nowhere near as bad as I experienced with my iBasso / Rock Jaw Arcana v2 set up). It’s never fatiguing, but sometimes you can wince a little.
 
Speaking of genres, one genre this little red box loves is dance. Oh, does it love dance. I don’t have a lot, because I’m not a massive fan. But I do have Ministry of Sounds 90s Anthems and I’ve never experienced dance music playback quite like it. Technotronic’s Pump up the Jam is incredibly well separated, with sound flying around the outside of your head. It’s a similar story with Gat Decor’s Passion. And if you flick that bass toggle… but more on that later.
 
But back to something more familiar with me, and Newton Faulkner’s Uncomfortably Slow. The guitar strumming in the intro is beautifully detailed, with great space and air. His voice is warm and well presented (and in front of the guitar), and the rest of the music arrangement is in layers behind his voice and guitar. Once the bass starts to come in, you get a gorgeous, rich sound that fills the space around your head.
 
Switching back to the FiiO X5ii’s own amp, and I observed that the warmth of the C5 goes, but the detail improves slightly. There’s something quite clinical about the way the FiiO goes about it’s business, and it’s a great sound, but I just like what the C5 adds in to the mixing pot. The FiiO is saying, “here’s the music, this is what’s been recorded, this is how it should sound”. The C5 then says, “yeah sure, but this is what you want to hear”. Don’t get me wrong, the FiiO is incredible, but the FiiO and C5 together is even better.
 
Snow Patrol’s “The Golden Floor” has many layers and a wide soundstage, and poor equipment struggles to reveal the subtleties and complexity of this song. The Fiio X5ii / C5 combo puts great depth between each layer and plays things nice and wide. Similarly with “Lifeboats” (from the same album) there’s some lovely layering going on. You just drift away with the song, even when you’re trying to listen in a critical way.
 
A note on volume - on higher volumes things can get a little messy, but this is volume that you might not need anyway – I certainly couldn’t listen to music at those volumes for an extended amount of time. If you need it that loud – either get your ears tested or invest in some noise cancelling gear!
 
Bass Toggle – 7/10
It’s a strange thing for me, bass. I do like hearing what the artist and producer intended to a certain point, in other words you’ll never catch me wearing a pair of Beats by Dre with the bass on the equalizer up to 10. But I do like to hear the bass. I like to know it’s there. I like it to be tight and punchy, with texture – underpinning the tracks as it were. Too much and it feels articifial. Too little and find myself pushing my earphones into my ears as if they weren’t in correctly.
 
The JDS Labs C5 has a bass toggle with has 3 options – off, medium and high. With the toggle in the off position, the C5 still delivers plenty of slam on Daft Punk’s Lose Yourself to Dance, and you never feel like you have to reach for the toggle here. On tracks that are bass light, such as Abba’s Voulez Vous, you are transformed to a 70s disco with deep, lush, rich bass that makes you tap your feet. And when rock or metal is the order of the day, such as the Foo’s Outside from Sonic Highways, the medium setting is just right to fill the bass line out nicely. But for the most part, I leave this bad boy in the “off” position, as it’s simply not needed. In some cases, the “High” setting is WAY too much for me, but I suspect bass heads will appreciate this.
 
It definitely works, and comes in handy. What’s beautiful about it is it doesn’t colour the other frequencies, nor does it drop the volume by a little. It’s either there, or not, depending on what you want.
 
Noise Floor
Surprisingly, I didn’t get the black noise I was expecting based on both the advertising and other people’s reviews. If anything, there’s a little more noise with this amp than with the FiiO’s in built amp. Maybe it’s just the Fidues, but there’s certainly a good degree of hiss going on. I can live with it, but I’d have preferred a completely black noise floor.
 
Conclusion
It’s always a gamble buying something you’ve never listened to before. Even more so when it’s such a subjective matter. I didn’t know what to expect with the JDS Labs C5. When I first turned it on I was disappointed. But it warmed up, and I warmed up to it.
 
It was a lush, warm, and smooth sound, but still manages separation and detail, and delivers fast and heavy songs with aplomb despite being so adept at the subtle aspects of music.
 
I can’t speak for other combinations of source and IEM / headphones as I’ve not really tested them. But with the FiiO X5ii and Fidue A73 it’s a glorious winning combination.
 
Actually, I’ve fallen in love with this little red box. I sometimes take it for granted and need to listen to other stuff to remind myself just how good it sounds (you get used to things).
 
 
 
 
 
 
 
 
 
 
 

This is quite simply a superb all-rounder. If you only need one superb DAC/Amp, then this will do the job nicely.

This C5D will give you what you want from the get-go.

Bass is beefy.

Midrange is clear and detailed, and neither forward nor recessed.

Treble is tonally accurate with no added harshness.

Soundstage is above average but some Amp/DACs are known to be 'slightly' more spacious.


The C5D certainly outperforms the FiiO X1 and X3 DAPs but has similar performance to the more expensive FiiOX5 DAP ($420). We just need an accurate DAC/Amp that doesn't change the music or add or take away for the sonic signature of the sound, the C5D does exactly this, with powerful 'clean' amplification and good dynamic-range, and the DAC translates the digital zeros and ones superbly. What more do you need?

 
First, I’d like to thank John Seaber at JDS Labs for the C5 review sample.
 
The JDS Labs C5 is the second generation portable amplifier designed by JDS Labs itself (replacing the outgoing C421) and is claimed by its creators to deliver “reference level performance”.
 
So does it deliver on its lofty claims or will it fall by the wayside? Read on to find out.

Design and Build Quality

Built with machined aluminum, the C5 is a very solid portable amplifier that feels like it could take quite a few knocks and keep going like a champ. The input and output jacks and the power and bass boost switches are very solid. The Volume control is different from the traditional ALPS potentiometers used on the O2 and CMoyBB in that it is a digital rather than analog potentiometer. JDS Labs claims this was implemented to eliminate channel imbalance at lower volumes. Unlike the lower end Fiio E11, the C5 can operate while charging.

Accessories

The C5 comes with an instruction guide, a 3 ft. Monoprice USB cable and a set of rubber feet.
 

Gain and Hiss

The JDS Labs C5 has two gain settings, which are toggled between by pressing in the volume control and, at 2.3x and 6.5x, is almost identical to the O2’s stock dual gain configuration and should provide ample power for anything short of orthodynamic or planar headphones.
 
There was no discernable hiss when listening to the C5, even with my most sensitive earphones.
 
One flaw the C5 has is its 2.2 ohm output impedance and all sources should ideally have an output impedance of zero ohms so as to prevent impedance swings but most and headphones, even sensitive balanced armature earphones should be fine.
 
UPDATE: I received a point of clarification from John Seaber himself, which states:

 

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Quote:

As long as headphone impedance is 8x larger than an amp's output impedance, the amplifier's impedance is of no concern. So for our C5, the minimum recommended headphone impedance is 8*2.2 = 17.6 ohms. In actuality, 2.2 is a worst case scenario. This specification is generally <= 2.0, meaning even 16 ohm headphones are typically acceptable.

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I rarely come across headphones or earphones with a lower impedance than 16 ohms so I assumed this would be a non issue for most users but seeing as I have an earphone in my possession right now with a low 12 ohm impedance (Sony's XBA-3IP), I should've mentioned it regardless. So, though the C5 has an output impedance of 2.2 ohms which admittedly isn't ideal, it may not be an issue for the vast majority of users, all things considered.

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Battery Life

The C5 is rated for 11 – 14 hours and I found the real world battery life to be closer to the 11 hour figure in my tests.
 

Sound Quality

Fantastic. Plain and simple. Its frequency response is flat, there’s no hiss to be found, no ultrasonic crud to muddy up the sound and its transparency and clarity are top notch because of it. To put it simply, this is the best portable amplifier I’ve ever heard, and that’s saying something.
 
Where the C5 really shines is in its bass boost switch, which has become something of a hallmark of JDS Labs’ amplifier designs. With the flip of a switch, you get a significant but not overbearing boost to low frequencies that, in practice, sounds great. At 6.5 dB of boost at its peak, the bass boost isn’t for everyone or every pair of headphones but it is satisfying to use with my HD 600s and my HiFiMan RE-400 and RE-262s. It goes without saying that bassheads should be quite pleased with the C5.

Comparison with the Objective 2

 
Now I know that it’s hardly fair to include a $189 amplifier in the same category as amplifiers costing less than $100 so I’m not going to judge it head to head with those amplifiers. Instead, I’m going to compare it to the king of “portable” amplifiers, the Objective 2.
 
So, after listening to the two side by side, how does the C5 compare? Well, after hours of listening to the two, I’m hard pressed to tell a difference, which is the best compliment I can think to give it. Not only does it have the power to adequately power my HD 600s in step with the O2, its transparency is nearly identically excellent.
 
Granted, the O2 is technically a portable amplifier as well and does cost less than the C5 but due to its rather bulky design that’s not at all pocket friendly, I’d really only refer to it as a “transportable” amplifier. Yes, you can bring it with you and yes, it runs on batteries but the O2 is simply too big and cumbersome to work well in a truly portable setup. The O2 is the type of amplifier you bring with you to listen to when you have a desk or table nearby while the C5 pairs well with similarly sized portable players and fits easily enough in a pocket (as long as you’re not wearing skinny jeans).
 

Conclusion

Overall, there’s no doubt that the C5 is a very capable, powerful and transparent portable amplifier that sounds fantastic with every headphone I tested it with. It feels like a solid piece of equipment in the hand and seems worthy of its $190 asking price from the JDS Labs website. While I don’t think it’s quite on the same level as the cheaper (but less portable) O2, the differences between the two are minute and considering the O2 has been compared favorably with amplifiers costing many times its price, that’s saying something. If you’re in the market for an excellent portable amplifier, the C5 shouldn’t disappoint.
 
Re-Posted from my site, Musical Musings