The buffer size is specified in kilobytes, where the first number determines the internal stream buffer (downloads the audio) and the second the output buffer (audio gets decoded). How big the buffer size should be depends on the files you send to the player via the Squeezebox server. In the slimdevices forum it is recommended not to use too large buffer sizes (e.g. so large that a complete sound file is loaded before it is played). The larger the buffer, the more stable the streaming should be, but of course this can also increase the latency.
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