I've recently bought these and set them up and they're fantastic. I bought them to connect to a new Pinnacle Soundbridge Home Music stick thingy (wireless streaming of internet radio and itunes playlists) and they work flawlessly. Sound quality is better than the Harmon Karden soundsticks I used to have for my Mac. These days the bass isn't cranked up like it was when I was in my teens because I like to listen to the mids and trebles these days, and these speakers really are nifty for that, but the bass can be wacked up without loss of quality if that's your bag.
I also use them plugged into the headphone jack of my ipod, and they connect to my Mac fine too.
I've not noticed the annoying hum/buzz that others mention (something which my ears normally pick up, believe me), nor is the adaptor too big either - although it does get in the way of a regular plug socket switch, but I use a multi-gang extension surge protector anyway so I just turn that off when I'm not using them.
One speaker has a line-in and a headphone jack, and that speaker also has the treble, bass and volume on/off nobs. Both speakers feel solid and weighty enough not to be knocked over too easily, look good and take up little space.
I'm so impressed with these (especially for the size) that I've now ditched my Denon Hi-Fi separates in favour of these and a pinnacle/ipod combo.