Review: CoolStream Duo

The original version of this review ran on December 23, 2013. We are re-running it in order to include the added section regarding the recently updated version, featuring Multipoint Technology.

About a year ago, we took a look at Auris’s freeDa, a small Bluetooth receiver that connected to most 30-pin Dock Connector-equipped accessories, allowing you to stream audio over Bluetooth. In the time since, there have been even more competitors (not that the freeDa was the first), one of which is the CoolStream Duo, a $40 music receiver that tries to do a few key things well.

About the size of a sixth-generation iPod nano, the Duo is a small, black, plastic device with a very simple design. The reason for the Duo name is that it can run as a plain and simple Dock Connector-powered audio receiver or provide its own power for use with unpowered or incompatible products. The battery, if you choose to use it, is rated to last about five hours of continuous play. There is only one control, a switch, on the top to choose between battery power or Dock Connector power. For Dock Connector power, the Duo is compatible with both 5V and 12V power sources. 12V is what many older docks use, especially if they were in the era of the third-, fourth, or fifth-generation iPods. Docks for newer devices that charge over USB are 5V. There is also a small LED to indicate the power and pairing status and a 3.5mm audio output on the same side as the switch. A 3.5mm cable is also included, which is always a nice touch.

Unlike the freeDa, which includes a battery, microphone, and audio controls, the $10 cheaper Duo focuses solely on music. As someone who has a car that has Bluetooth, but only for phone calls, I really appreciated this. Devices like the freeDa often fought to be the default source for things like Siri or phone calls. The Duo does not.

Still, a device like the Duo is only as good as it sounds, right? In a few tests of different kinds of music, iTunes Radio, and numerous podcasts, we found the audio signal to be clear and just a bit quieter than a direct connection on a variety of devices, including a few older speaker docks and a direct connection to a car. This is a limitation of most Bluetooth receivers, but doesn’t seem to affect audio quality. As for range, in some unscientific testing, things started to get staticky around 20-25 feet, fairly close to the 30 feet maximum rating.

The nice thing about car and dock use is that the Duo turns on and off with the device and pairs automatically when not running off of its battery. While on battery power, it simply pairs automatically when turned on.

There is one last use for the Duo—maybe they should call it a Trio—turning normal headphones into Bluetooth headphones. One can simply connect a pair of headphones to the 3.5mm output and use the device’s volume control to adjust volume. This may be useful for running or other times when an iPhone in a pocket or armband might be nicer.

If there were some things to complain about, it would be nice to see the battery level on an iPhone’s display, like the freeDa. Also, the switch on top is not labeled, so you often need to remember which position is which or play with it with trial and error.

Overall, we were rather pleased with the Duo—it’s relatively inexpensive and does a few things quite well. It pairs quickly and maintains a strong signal, can make older docks work with a newer iPad, iPhone, iPod touch, Mac, or even an Android device. The ability to be powered over 12V, 5V, or its own battery, gives it an edge to be used in the widest possible variety of situations, and can even put some excellent old iPod-only sound systems back into use.

Multipoint Technology

In September, CoolStream announced that the Duo received a minor update to include Multipoint Technology, which allows pairing of two different devices to one Duo via Bluetooth at a time. Most Bluetooth audio devices are designed for one person’s use, which is fine, but what if you decide to use the Duo in an environment where multiple devices would need to connect to one audio device? Besides sharing an audio device with two devices of your own, this could for different family members, a friend, or significant other.

I tried it in the Duo’s natural application, the car, while driving on a trip with a friend. After pairing both of our iPhone 6s running iOS 8.0.2 (the process was easy), we were able to alternate connecting the devices for who was playing the role of DJ. While it would be nice to support even more devices (think iOS hoarders in various-sized households), this is a great start. After updating to iOS 8.1, the Duo still has been working flawlessly.

Other than that, the Duo hasn’t had anything else noticeably changed, so our prior comments fully apply.