I’d like to thank John Seaber and the folks at JDS Labs for the C5D loaner unit.
The C5D ships with a 1.5 foot USB mini-B cable, a set of four rubber stick-on feet and an instruction manual. A Spartan lineup, to be sure, but it gets the job done.
Design and Build Quality
Identical to the C5 in shape and size, though with a couple of added features, including a switch around back to allow the C5D to charge from a connected USB source or run strictly from battery power and a two-stage bass boost switch on the front with two boost options, instead of the single boost option in the original version of the C5.
Though I thought the switch that allows one to disable the charging circuit of the C5D and run on battery power alone was a rather frivolous feature at first, I quickly learned that it’s hugely beneficial when using the DAC with my iPhone. I connected another USB DAC/portable amplifier I have, the MUSE PD1+, to my iPhone and it advised me that the connected accessory couldn’t be used because it consumed too much power, despite having its own battery. So a point for JDS Labs for realizing the necessity of such a feature.
Clad in an aluminum casing, the C5D feels sturdy and reliable, like it could easily handle being thrown into a bag or pocket every day and endure like a champ. Of course, I handled my demo unit with care but its solid feel instills confidence in long-term durability.
Unfortunately, my demo unit shipped with a weak battery so I wasn’t able to evaluate its performance accurately.
iPhone 5S – Apple Camera Connection Kit
Google Nexus 7 FHD – USB Audio Player Pro – USB OTG Cable
If you’ve read my review of the JDS Labs C5, just apply everything I said there to the C5D, as its amp section is audibly identical to my ears, namely, excellent. The C5D, like the C5, is designed for sensitive headphones and IEMs, so its power output isn’t very high compared to other portable amplifiers like the Fiio E12 but despite that, it is still able to drive high impedance and low efficiency loads like my Sennheiser HD 600 and HiFiMan HE-400 to nice and loud levels without sounding strained, like some other portable amplifiers will with headphones like these.
The all-in-one design of the C5D makes it very portable and usable around the office. I’ve been using it almost exclusively with my iPhone 5S, loaded with a mix of high-resolution lossy AAC and MP3s and performance has been stellar.
It is a bit disappointing that the C5D doesn’t have line-out functionality built in, just in case you wanted to use it as a dedicated DAC for a more powerful amplifier (like the O2, for example) but I didn’t find myself wanting for more than the C5D was capable of delivering. Of course, this may change if I ever get my hands on a set of power-hungry planars or 600 ohm Beyerdynamics. JDS Labs offers a conversion service to change the line-in jack to a dedicated line-out from the DAC but the downside of this is that you lose the ability to connect analog sources.
Another minor flaw is the audible “pop” that comes from the amplifier when it’s switched on. Not a big deal but it’s worth noting.
Yep, that’s it.
The C5D supports 24 bit/96KHz decoding over USB and performs excellently in that capacity. Listening to a few 24 bit high-res test tracks I loaded onto my Nexus 7, the C5D sounded lovely with my Sennheiser HD 600s, so much so that I had to tear myself away from my listening in order to go to bed that night. That being said, whether or not there is any tangible benefit to carrying around 24/96 high-res files is up for you to decide as the audible differences between two lossless 16 and 24 bit files are negligible at best.
But I digress. The important thing here is that the C5D is more than capable of decoding high-res files and amplifying them at a level that will make your headphones sing. Compared head to head with my O2 + ODAC, the C5D was practically identical, subjectively speaking, which is very high praise in my book.
As both a portable amplifier and DAC, the JDS Labs C5D is superb. Though its published battery life is relatively short compared to some other portable amplifiers, the C5D’s feature set and overall performance more than make up for it. I wish its DAC had a dedicated line out for use with more powerful amplifiers but that’s taking the C5D out of its element to a certain degree. It’s meant to be used in a portable setting and in that capacity, it excels, though I would hardly say someone was crazy for using it as an all-in one desktop amplifier and DAC option. The C5D has the audio quality to perform well in that respect but I’d still recommend the slightly more expensive O2 + ODAC for desktop use.
At $250, JDS Labs’ C5D certainly an investment and one that only audiophiles can easily justify but if you’re looking for stellar audio performance from any and everything that supports an external USB DAC or a simple line-out, the C5D is likely one of the best portable amplifiers in the business and definitely the best I’ve ever heard.