Now the company's replaced that 5 series, also referred to as the A5, with the 5+. While the new "plus" model leaves off one feature (built-in AC power output) and jacks up the list price (bringing it up to $400), we're happy to report that these guys definitely sound better, once again delivering excellent performance and features for the money.
The key thing to note about Audioengine speakers is that they are bookshelf-style speakers masquerading as PC or "multimedia" speakers, as these things are apt to be labeled. But unlike classic bookshelf speakers, these Audioengine models are powered (via a standard AC plug); there's no need for a separate receiver or amplifier, so you can use them with any audio source. Think of them as an old-fashioned stereo, but without the head unit, as the connections are all on the back of the left speaker.
The larger 5+ series is more industrial-looking (read: less stylish) than the 2 series and appears to share some heritage with monitor speakers you'd find in a recording studio. They're available in either black or white, as are the 2s. There's also a bamboo version of the 5+ series that costs $469 and looks significantly swankier--it's really nice if you have the decor to go with it.
The Audioengine 5+ speakers look to be about 10 percent bigger than the earlier 5 series. While they're similarly sized, measuring 7 inches wide by 7.9 inches deep, the 5+ speakers come in at 10.75 inches tall, while the older model came in at 10 inches.
The other key specs haven't changed. The speakers have a 5-inch Kevlar woofer and a 20mm silk dome tweeter. Because the left speaker houses the amplifier (50 watts per channel), it's heavier than the right speaker. Unlike the 2s, which have ports on the front, the 5s have ports on the rear.
It's worth noting that both the 2 and 5+ series Audioengine speakers come nicely packaged, with cloth covers over the speakers and cables. The left and right speakers connect to each other with "real" speaker wire (included) and you also get an input cable that allows you to connect your PC, or anything else, to the 3.5mm aux input on the back of the left speaker. The use of standard cables means that--unlike some speakers with proprietary connections and cables--you can invest in custom-length cables that are as long or as short as you'd like.
One final design note: these guys have no speaker grilles, which can be an issue if you have small children or animals who might decide to poke at them and potentially damage the speaker.
So what are the differences between the 5 and 5+ speakers? Well, Audioengine says that the 5+ series has a new thermal system for keeping the amplifier cool, and the designers also changed up the connectivity a bit.
Instead of an extra 3.5mm aux input on top of the left speaker along with a USB port for charging portable devices, that audio input is gone and the USB port has been moved to the back of the speaker. That's a good thing because it means you can hide whatever you're charging behind the speaker instead of having the USB cord sticking out of the top of the speaker.
To be clear, the USB port is only for power, not for reading audio files; it also doesn't allow pass-through syncing with PCs. But that combination of USB power plus audio input allows you to charge your iPod/iPhone with a USB cable while you're listening to your music. And though the cables make the 5+ series a bit less appealing to the eye than a standard iPod dock, the combo is far more universal in its compatibility: you can charge and play any USB-powered audio device, including pretty much any smartphone or portable media media player. Unlike some USB power sources, the 5+ series speakers also have enough power to juice up tablets--this worked just fine with an iPad 2 and a Kindle Fire.
On the older 5 series, Audioengine integrated a full-on AC power jack into the back of the left speaker. The company touted the fact that you could plug an Apple AirPort Express directly into the outlet, turning the speakers into an iTunes streamer via Apple's AirPlay functionality. Of course, that outlet could also power any other audio source--anything from a Sonos or Squeezebox streamer to a CD player. But again, that outlet's gone now, though most people probably won't lament its loss too much.