It gets even better: the second 3.5mm input on the left speaker's backside is located near a full-on AC power jack. Audioengine touts the fact that you can plug an Apple AirPort Express directly into the outlet, turning the speakers into an iTunes streamer (via Apple's AirTunes functionality). Of course, that outlet can also power any other audio source--anything from a Sonos or Squeezebox streamer to a CD player.
Note that you can't toggle between inputs; both are always active. That's either going to be a feature (say, the ability to listen to music from an iPod while being able to hear the bleeping and blooping from your PC) or a bug (the constant need to mute one audio source while listening to the other), depending on your point of view.
Speaking of controls: no remote is included, and we should point out that the volume control button is on the front of the left speaker. Unlike with the 2s, that volume knob doesn't double as the power switch; there's a separate power toggle on the back of the speaker. However, Audioengine has equipped the 5s with an autosleep power-save mode that kicks in after about 10 minutes when no audio passes through the speakers. That said, some people have complained that the speakers make a sound when the power-save mode kicks in--and it can be fairly loud if you have your volume up high--which you may find annoying.
Also of note: though the Audioengines aren't technically "certified for iPhone," they are magnetically shielded. We didn't experience any GSM interference from the iPhone (those annoying clicks and buzzes that can afflict nonshielded speakers), even when we left it directly on top.
Audioengine sells some accessories, including the S8 subwoofer ($350) and a couple of wireless adapters (the W1 and W2) for its speaker line. The subwoofer connects via the red/white RCA stereo outputs on the left speaker's backside. It would obviously allow you to get more bass and even richer sound, but the appeal of these speakers is that you can really do without the sub.
It's hard to quantify just how much better the Audioengine 5s sound than the Audioengine 2s, but they definitely deliver bigger, richer sound with deep, tight bass, and excellent clarity--and they play very loud. With higher-end PC speakers you just get fuller, smoother sound that has that much more detail, and when you listen to these guys, you start to hear stuff (i.e., individual instruments) in your music that you weren't aware was there. They easily best more-expensive iPod speakers out there, including those from Bose and B&W, which retail in some cases for twice as much.
When we review PC speakers, we like to throw an eclectic mix of music at them, as well as a couple of action movie and games (usually a first-person shooter or two). We also like to do a little jury testing, and for this review, we pulled in Steve Guttenberg, who reviews home theater speakers for CNET and had previously praised the Audioengine 2s and the Audioengine P4s (unpowered, passive bookshelf speakers) in his Audiophiliac blog. Steve thought the Audioengine 5s sounded great and were clearly superior to the 2s, but he liked the 2s for their smaller footprint, sleeker look, and more affordable price tag.
It's true: For some, this model will just seem too bulky to leave sitting on a desk. They truly are bookshelf speakers with--as we said--a more industrial, monitor flair to them. However, the bottom line here is that you're going to be hard-pressed to find a 2.0 system that sounds better, particularly at this price point, and that has the 5s' connectivity options. Yes, we could quibble about there not being an integrated iPod dock and remote, but in the end, the extra input and USB port on top of the speaker, combined with the speakers' exceptional sound, make the Audioengine 5s worthy of an Editors' Choice award.