Disclaimer: PlusSound is an American company that mostly specializes in after-market cables. They however do also have their own portable amplifier the Cloud Nine. I got the amp free of charge for this review.
Ever since Nathan reviewed the PlusSound Cloud Nine (CN) I had been dying to hear one. PlusSound got word of that and they decided to send me another Cloud Nine amp for review. At the same time I also got a superb Apollonian+ IEM cable I have been using with the Earwerkz Legend R, an Apollonian+ cable terminated for Audeze that I have been using with my LCD-XC and an Echo+ Interconnect which has been my to go to interconnect since I got it.
When you look at Nathan’s gorgeous pictures of the Cloud Nine, you can immediately see it’s a pretty basic amplifier. It doesn’t have the fancy enclosure of an ALO or CypherLabs amps and it’s more of a back to basics kind of unit. I quite like that approach. The Cloud Nine is a simple looking portable amplifier intended for use with In-Ear Monitors and low and high impedance headphones. The Cloud nice was designed primarily on improving sound quality and pretty much explains why it has such basic but lovely enclosure. The anodized aluminium shielded enclosure, volume knob, and screws are custom made specifically for Cloud Nine.
The Cloud Nine isn’t the smallest of portable amps and it measures about 2.3″ x 4.5″ x 0.95″ and weighs 3.2 oz (without batteries). The CN actually is an 18V (2 x 9V!) battery powered amp. The down side is that you will have to change out the batteries. That means either replacing the stock delivered Duracell or buy rechargeable ones like I did. I have a mixed feeling with the choice for the 9V batteries but the upside is that you get an extremely effective, powerful and clear sounding amplifier in return. I was pleasantly surprised by the durability of the 9V batteries: I expected them to die on me under 10 hours but I’ve listened to it a whole lot and can you believe I’m still on the original set? All 9 volt batteries (Alkanine, NiMH, Lithium) will work with this amplifier and it can run from 20 hours to 80 hours. Expect long battery life, seriously!
A related down side of the Cloud Nine using 9V batteries is that they have to be easily accessible to change them out. To allow this PlusSound decided to use a thumbscrew system on the back and well it looks awful as we’re not used to seeing that on modern day amps. Then again, contrary to Nathan, I found these thumbscrews very easily accessible and easy to use. Sure it doesn’t look stellar and you can’t put the Cloud Nine up straight but it sure is handy.
The Cloud Nine has 3 gain stages (1x/0dB, 5x/10dB, 10x/20dB) and because of it sounds superb with all my gear from my most sensitive custom IEMs to the hardest to drive HE-500 Hifiman. On the inside you’ll find a precision amplifier followed with dual mono operational amplifier integrated circuits in the output stage. I have to admit I have a soft spot for Dual Mono designs. The entire amplifier goes through cryogenic treatment to improve durability and sound quality but I’m not really convinced of the whole cryo treatment myself.
Does it live up to its expectations?
With a power rating of 1.28W into 32 ohm, 1W into 50 ohm, 250mW into 300 ohm and 120mW into 600 ohm you can clearly see the Cloud Nine is no slouch, it’s extremely powerful for a portable amp of its size. Not only is it powerful: THD:~0.0009%!
Sound on Page 2