The first ever portable amplifier I owned was the JDS Labs cMoy BB. I had just got into the hobby and the obvious step for me to take after getting some new earphones was to purchase an amplifier, so for my Birthday my Dad bought me a cMoy as I had said how cool I thought the design was. I loved what it did, giving something extra to my iPhone’s sound and eventually being able to power my first high impedance cans, the Sennheiser HD580. My next amp was the infamous Objective 2 and although I purchased the Epiphany Acoustic version due to them being based in the UK, in the US, JDS Labs are the main manufacturer of this amp and I was tempted to go with them again as their customer service was so good as well as being very personal the first time around. I have ranted on a bit now but both these amp have a very special place with me, as they were the first ever products that I wrote a review for and they lead me on this amazing journey through audio. That journey has taken me to many devices but I am now back with the latest JDS Labs portable amplifier, the C5. It has a price tag of roughly 120 pounds not including shipping, which makes it the most expensive JDS Labs amplifier they currently have on the market.



First of all, I am very impressed by the design of this amp, especially when considering John Seaber, the man behind JDS Labs, started off as someone selling his DIY cMoys on eBay. It is clearly apparent he really has come along way. This particular amp is very sleek looking and comes in a variety of colours, a really nice red, a slate and a black. That combined with the matte finish and the metallic silver front and back plates and you have a very attractive and professional looking amplifier. The feel of the C5 is also very good, very smooth in the hand and the knowledge of the all metal design will be able take a few hits before getting even close to breaking. The simple rectangular design also leaves me very happy and while it might sound like something you expect from an amplifier, I have seen some really stupid designs lately like the cruise from ADL that is just not practical! I like to be able to stack my amp with my DAP such as my MS-AK100, iBasso DX50 and of course the iPod Classic. This stack is perfect as its form allows it to just sit tightly under the player. In terms of size I also have no problems with it. At 4 inches it is just a bit longer than my AK100 and shorter than an iPhone 4. It is 2 and a ½ inches wide so just a tiny bit wider than the devices I have used it with.  A very modest ½ inch deep makes the stack a comfortable size; not too bulky. It also has almost identical dimension to my iPod Classic and it was clearly designed with that in mind.



Feature wise, this has a USB charging point and a clunky on switch on the rear of the product. On the front we have the 3.5mm headphone output and the 3.5mm audio input. You also have the bass boost switch that adds 6.5 decibels at 80 Hz and lastly the digital volume switch, which is a bit different to use than your usual pot. Not taking into account the benefits of a digital control, I do really prefer using a pot to control the volume in comparison to the slider just because I know where I am, what volume I use on each headphone etc. and there is no way of being able to identify what volume it has been left on and if there is a chance of blowing my ears off so I end up just setting it really low every time. Also because it has no profile it easily gets covered by an interconnect, not allowing easy volume control. My last complaint with it is that each step seems to sometimes be a bit too much with sensitive earphones and it does not allow the finer volume adjustments I sometimes like to do. Benefits of the digital control are the fact that you just do not find any sort of channel imbalance with any earphone or headphone in my possession, which is just great and not easy to pull off. That being said I still do not see how a normal pot could not be used in conjunction with the digital control.There is also a gain switch by clicking the volume control. In standard it is 2.3x and it is boosted up to 6.5x.


I have been told the JDS Labs have updated the design so the control is much more accurate when in use.

Driving ability testing and for this brought out the Sennheiser HD580 that is 300 ohms and the HiFiMAN HE-500 that despite the low Ohm value, it needs a lot of power purely because they are planar magnetic. To start with I used the HD580 and initially volume was not a problem in the slightest. Most of the sound spectrum was present and with authority but the treble was left slightly fatiguing at times and the soundstage was not quite as big as I have heard it. For the most part it got a clear thumbs up and I would quite happily use them together if I had too. The next match up was always going to be a bit harder, the HE500 are very demanding and no portable amplifier I have ever owned has truthfully managed to supply the demand of the HE-500, although I know there are some out there that can. I was quite surprised about the sound quality I got from this pairing, no it is no where near potential but I could listen to this quite happily, it could keep me happy while waiting for something that can do the job 100%. To be fair, all this matters very little to me as its main focus should be driving portable cans and IEMs that tend to be low impedance and more sensitive and that’s the sort of gear the following sound impressions will be based on. This does not have a perfect output impedance of less than 1 ohm but when testing with earphones that are not the ideal 17.2 ohms (using the 8x rule), I came across no problems.


(Left to Right) MyST Port Amp, ADL X1, C5, Tube Amp TA-1, Sunrise AM-P1, Lear FSM-02 v2


(Top to Bottom) C5, AM-P1, FSM-02 V2, Port Amp, X1, TA-1


First of all I just want to talk about the bass boost. With the cMoy BB I used to own, it was too much, you hit the switch and you were immediately overwhelmed by thick, muddy bass and it washed out the rest of the spectrum. Since then, I have had the Hippo CriCri that added what I would say was perhaps a too subtle bass boost but very usable and the DigiZoid Zo2.3, a dedicated bass boost, and a very impressive one. Compared to the cMoy and the Hippo this is certainly more successful. The 6.5 decibel boost is obviously very noticeable and adds an easy to hear change in signature but it’s not muddy, bass remains tight and certainly seems to add musicality and fun. It does loosen the bass a little bit and we do get some extra decay and warmth but not too a stupid degree. 80 Hz was obviously a sweet spot because get a more visceral sub-bass kick as well while the midrange was thicker and warmer, it still had obvious presence and held onto a lot of its detail. If your using already very bassy headphones then it may get too much but I tend to have a rather balanced collection of headphones and with most of them, it went down a treat!



(Bass boost now off)



The sound of this amp was well balanced like I would expect from a good portable amplifier and I found it ever so slightly forward in general presentation. Dynamics were good and so was extension either side, especially in the higher frequencies where presentation increased the airiness which was nice. This helped the soundstage to become considerably wider with some great right to left imaging and height but the sound was a bit thin with a lack of depth. The bass was tight and has a well held together impact and does not come across as warm or too big (but you know what to do if you want it to be). The midrange is very clear, detailed without grain. It is airy and forward with a slight bit of a tilt to that upper midrange so clarity comes across very easily. The bass and midrange seem to have just the right amount of presence while remaining very clear, with just great detail retrieval and remaining true to the source. The treble can sometimes get a bit aggressive, especially if paired with a headphone or earphone that already has peaky or bright treble. Now I am not saying this is a bright amp just a rather revealing one and it will display sibilance and quite a shrill treble if that is the case and does not try to hide or stop it. The background was not as black as other amps like my MyST PortAmp or the Objective 2 which are almost almost dead silent while it still faired very well against more powerful amps like the Tube Amp BL-2 or just down right noisy amp like the ADL X1. Fortunately it did not suffer from EMI (phone)interference.


(Left to Right) iRiver Mezzo Soprano MS-Ak100, iBasso DX50, C5, Apple iPod Classic


Apart from the odd synergy issue regarding the treble, it was a very nice, clean amp that has paired beautifully with both my iPod Classic and MS-AK100 and a lot of earphones with the likes of my Lear LCM-5 and HiFiMAN RE-600 being some of the more exciting pairings, especially with the option of that bass boost if needed. The build and finish of this amp make it a really class product for the price and I think this is the stand out amplifier under 150 pounds for portable use. As far as I am concerned, no Fiio, Firestone Audio or Hippo touches (the Sunrise Audio AM-P1 is maybe a notable option of you want a very lush, warm amp) it, and although I do have better performing amplifiers, you will be set back at the least a 100 more pounds for them and to me, that is moving clearly into another tier. If you’re on a budget and this is in your price range, I would look very seriously at the C5!


with the iBasso DX50

Sonny Trigg