Best way to expand WLAN for streaming compressed FLAC files?

the "best" way if you are concerned about bandwidth availability is probably to use multiple access points and link them using cables of some sort. The wireless link(s) thruput is the limiting factor, so only use it where you have to.

So - Cat5 and 100 Base-Tx is probably best, but if youcannot get the cables around the house then Homeplug or similar would connect the boxes via the mains. some of the hardware for Homeplug is country dependent (ie. last time i checked the Netgear stuff is only for 110v, so no use to me in Europe).

if you have some cabling, then linking fixed devices such a s video sender via cable will also free up wireless capacity.

if you have to use wireless for several links, then thry to use 802.1a for some or all links - there are more channels available, and since the kit costs more, fewer users causing interference.

I can not find Homeplug AV equipment. Homeplug 1.0 only goes up to

SD

Netgear 4 port 85 Mbps homeplug unit

i need to stress - this is something i would only use if i cant pull cables, since every Cat5 gives you 100 Mbps full duplex, and no shared medium where other conversations may slow you down (unlike wirless or homeplug)

the newer version claims 85 Mbps - since it uses the wiring as an access bus, there is going to be some overhead, so expect a fair bit less than that in practice.

it isnt AV gear - this is networking. The idea is to build a set of network plumbing, and plug whatever you want into it (using Ethernet which is the common interface)

just about any modern laptop / desktop / high end games console comes with Ethernet, and it is available on personal video recorders and similar gear.

Devolo and Netgear's current 85Mb stuff is autoswitching.

Typical FLAC bitrate is 800-1100 Kbps (about 1 Mbps), for which even Homeplug