OP probably means Primephonic.com, a classical only service They transmit in 44.1/16 or 48/24 but their streams are unmarked.
Your need a program like MusicScope, which is no longer available, to see what they, or any other streamer, is actually sending. My own inquiry suggests that Primephonic, unlike several others, actually delivers what they promise.
By the way, file size (FLAC or otherwise) is no indicator of SQ. It only gives you the size of the container, not of the non-zero bits within.
Your need a program like MusicScope, which is no longer available, to see what they, or any other streamer, is actually sending. My own inquiry suggests that Primephonic, unlike several others, actually delivers what they promise.
By the way, file size (FLAC or otherwise) is no indicator of SQ. It only gives you the size of the container, not of the non-zero bits within.