Allow me to state what's obvious to many BeoWorlders: BeoLab active speakers are an incredible shortcut for today's digitally savvy generation. You literally do not need an amplifier between your source and the speakers - the amplifier is built into the speakers.
You could actually just connect a pair of BeoLabs directly to your computer or an AirPort Express unit, or similar component. However, that's not advisable for several reasons.
1. BeoLab speakers are very good - they deliver excellent sound, and are capable of a very natural performance. You should give them the best possible signal.
2. AirPort Express and laptop computers have inexpensive, low-spec digital-to-analog conversion components (DACs). When you use the analog signal they provide, and connect that directly to your BeoLabs, you are not achieving what your speakers are capable of.
3. There's also a safety issue. If you've already tried this direct analog connection, you will have noticed that your speakers make quite a lot of noise when you remove or insert the connecting minijack; and you may also occasionally have served yourself a blast of sound because the volume setting was too loud. To protect your speakers and hearing you should have a unit between the Airport Express or computer, and the speakers.
4. The Airport Express minijack-out can deliver both an analog and a digital signal. If you use the latter, you won't be using the low-spec DAC inside the Airport Express to transform the digital signal to a signal your speakers understand.
5. You should therefore get a Digital-to-Analog-Converter (DAC), and run a Toslink optical cable from the Airport Express to the DAC. These cables are inexpensive, and all you need to make certain is that the cable has minijack Toslink at one end, which is the one you'll be inserting into your Airport Express (or computer). You then connect the cable to the Toslink IN on the DAC.
6. If your BeoLabs have RCA-connectors, then you can just run RCA audio cables from the DAC to the speakers. But most BeoLab speakers have only Powerlink connectors. No problem, companies such as Sounds Heavenly (see link below) can supply you with an RCA-to-Powerlink cable that you can use to connect the DAC to the speakers.
Main benefits:
1. No scratching or sudden sound explosions due to changes in impedance as you remove or insert the analog minijack plug, while the speakers are switched on. And no need to switch the speakers on or off.
2. A good DAC sends no signal to the speakers when it isn't receiving a signal, which means the speakers will power-off after a while when not in use.
3. DACs with volume control can be used to set a maximum working volume, to protect them and your ears - BeoLabs are powerful.
4. You get very good conversion of the digital signal, ensuring your speakers are fed with CD-quality sound if your files are AIFF/WAV/or Apple Lossless (ALAC).
5. If you get a DAC with headphone amp's you can also use it to listen to headphones from the DAC, which is also better than just connecting them directly to the computer.
Volume control, remote control with iPhone/iPod Touch/iPad is easily achieved, using the free Remote app from Apple, or using other apps, including those developed for Squeezebox, Sonos, etc.
There are various threads here discussing different DACs and solutions - but all of them adhering to the basic principles above.
