Bluetooth is a way to wirelessly stream audio over a certain distance between devices. There are different Bluetooth codecs, such as AAC, AptX, and LDAC. Bluetooth codec sound quality is determined by the algorithm (codec) used, the transmitters and receiver quality, as well as the file bitrate. The bit rates of all current Bluetooth codecs are lower (or in the case of AAC and AptX) much lower than lossless FLAC. The bitrate of an AAC stream is 254 kbps, whereas a lossless file normally contains 1441 kbps or more of information, depending on the sample rate and bit depth. If you want the best sound quality, using Bluetooth is not the best way to go. If possible, use a wired connection or stream over Wi-fi, which audio companies such as Sonos and Bluesound support. Wi-fi streaming has enough bandwidth for lossless file playback. If you choose to play a lossless file over Bluetooth, don’t expect to be overly impressed with the increased sound quality of a lossless or hi-res file. I would expect you not to be able to hear a difference. Any benefits gained from switching to lossless will be nullified if the file is listened to over Bluetooth, where the bitrate is capped well below the bitrate of the source file you are trying to play. With all this being said, the introduction of the new Bluetooth LE codec is touted to equal or even surpass the sound quality of lossless FLAC. Only time will tell whether this claim is in fact true. Until LE becomes standard, it is best to avoid Bluetooth for the best sound quality.
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