SonyStyle USA - SRS-T55
I wrote this one for Amazon:
Music from atop the cabinet filled the (small) room. It was as loud as we would want, and the sound was remarkably clear. The slender speakers and the elegant iPod were almost invisible.
"There are times that I really feel I'm in the 21st century", Emily said, "This is one of those times."
Very impressive. The speakers are a bit bigger than I expected; I think the SONY SRS-T77 is more compact. It's the only comparable product; but it's twice the price of the SRS-T55. Mind you, these are so good I'm tempted to keep them by my iBook and buy the SRS-T77 for the office.
The speakers folded up are 2x3.5x4 inches. The battery compartment, holding 4AA batteries, makes up a fair bit of the size -- to be significantly smaller the device would probably need an internal rechargeable lithium battery and the price would be much higher.
SONY claims 24 hours of battery life at 10mW output. Maximum output is 1 W/speaker or 2W. You can buy an external SONY adaptor (ACE60HG) for about $20; I think it's a 6V/700mA adaptor. SONY of course says not to use any other adaptor, a possibly compatible RadioShack universal charger is about $16 -- not much less.
If you think you'll buy the charger, however, remember than the SRS-T77 comes with a power adaptor. Once you add in the cost of the adaptor you should consider getting the SRS-T77.
I thought that for convenience and portability I'd run off batteries, but we'll see. I may end up using them so much at home that it'll be worth buying the SONY power adaptor.
The speakers will work when powered off, but my iPod doesn't put out a strong enough signal to use for long in that mode. If you want to use your iPod as an alarm clock, and you're a light sleeper, this may come in useful however. I think leaving the speakers turned on overnight might drain the batteries. I'll experiment a bit with this.