The G4 Cube comes with a pair of crystal-clear, eyeball-shaped speakers created by Harman Kardon and Apple. They belt out 20 fair-sounding watts (10 per channel) of sonic force between the frequencies of 80Hz and 20KHz -- all through the power of the Cube's USB port. They are able to achieve this wattage from the USB bus because of the efficiency of the digital amplifier found in a box along the USB cable. The amp even has an analog headphone jack -- great because the Cube itself has no I/O for speakers or microphones (other than via USB add-ons). The Cube Speakers require "special" 10-watt USB ports to work at full volume. The Cube has these ports, as do all Apple ADC monitors. These special USB ports are sometimes called 20-watt ports by Apple, because the two ports share a single 20-watt supply of power, however, the Cube Speakers only use 10 watts per channel. Regular USB ports only supply 2.5 watts - so don't bother trying to run your original Cube speakers off your USB hubs or keyboards.

Although you may think the bowling-ball hole grills that cover the Cube speakers are attractive, Apple actually intended them to be removed for better sound quality, so go ahead and take them off! The digital amplifier module includes locking loop for theft prevention and miniplug for connecting stereo headphones

The Apple Pro Speakers, which look identical to the Cube's USB orb speakers, use a proprietary digital audio connector rather than USB; this connector is found only on G4 towers (not Cubes) made January 2001 and later. In other words... no, they are not interchangeable.

Can I use an iSub subwoofer with my Cube speakers?

Yes you can, but only if you are running OS X 10.1 or later. As overheard in the Forums: " I have my iSub connected via a bus-powered hub off the Cube and it works just fine with the stock ball speakers that came with the Cube. The separate volume control sliders and mute checkboxes make it easy to set the sound balance between the two speaker systems. About the only problem I've found is that the Mute button on the Apple Pro Keyboard (it would be numbered 'F18' - right next to the Eject button) only mutes the main speakers — the iSub keeps on thumping!"  Mac OS 9.x does not allow use of the USB-based Cube speakers and the iSub at the same time. OS 9 does not have the capability to utilize multiple audio-out USB connections at the same time, so you can use one or the other, but not both.

How about SoundSticks?

If the bundled speakers don't muster up enough juice for you -- i.e. you want better, richer sound -- you may want to check out Harman Kardon's SoundSticks. Based on the original design of the iSub , the powered, 3-amplifier subwoofer doles out power to two 10-watt totem-like satellites, each with four 1-inch transducers for a total of 40 watts of sweet noise. As if H/K and Apple hadn't confused us already by making the Cube's USB speakers and the digital audio Apple Pro speakers look identical, they made the iSub and the subwoofer for the SoundSticks look identical too. Again... they are not interchangeable.

What other speakers can I attach and how?

A few recommendations...

The Griffin Technology iMic USB Audio Interface: The iMic™ universal audio adapter is a USB device that adds a stereo input and output to your Cube. This allows the connection of virtually any microphone or sound input device. The iMic supports both line and Mic level input as well as line level output for any USB capable computer. Although in principle the iMic can record and emit sounds at 24-bit resolution, Apple's audio manager limits it to just 16-bit resolution.

Installing the iMic is trivial - plug it into a USB port and Apple's built-in audio driver takes over. Once your Mac has recognized the iMic, you'll see new audio input and output sources in the Sound control panel. Select a source, and you can immediately record sounds from anything plugged into the microphone port or listen to headphones or speakers plugged into the output port (depending upon which port you've selected). For $35 of ease of use, you won't find a better solution; but for professional use, you may want to take a look at the Griffin Powerwave USB Audio Interface & Amplifier, which has stereo RCA jacks and minijack ports and includes the cables necessary to connect the unit to your stereo or iPod.

The ONKYO MSE-U33HB USB Digital Audio Processor or the ONKYO SE-U55 External USB Digital Audio Processor ( PC / Mac ) will allow you to use your favorite analog speakers with the Cube, as well as provide a versatile input interface.