SqueezeBox will stream music loslessly from a PC. It generally requires a PC to function. The regular model of Sonos includes a storage server, so it stores your music as well. Sonos has additional functionality which allows you to do multi-room stuff. Visit http://slimdevices.com and http://sonos.com to learn the basics.
I haven't been able to compare sound quality directly. I have a SqueezeBox (latest version) and it has good sound quality for its size and price. You can also go digital out from a SqueezeBox to a good DAC to make a big jump in sound quality. The DACs in the SqueezeBox are good, but they are surrounded by a bunch of electronics and they have a wimpy power supply. I don't think you'll find the audio quality to be bad in any way but you probably won't be amazed by it either. Jitter on the digital outs is good but not outstanding - my RME Audio Digi 96/8 PCI card has noticeably lower jitter.
I haven't been able to compare sound quality directly. I have a SqueezeBox (latest version) and it has good sound quality for its size and price. You can also go digital out from a SqueezeBox to a good DAC to make a big jump in sound quality. The DACs in the SqueezeBox are good, but they are surrounded by a bunch of electronics and they have a wimpy power supply. I don't think you'll find the audio quality to be bad in any way but you probably won't be amazed by it either. Jitter on the digital outs is good but not outstanding - my RME Audio Digi 96/8 PCI card has noticeably lower jitter.