I wouldn't expect it to be buffered in compressed format.
I've seen 10 seconds mentioned - even on a home unit - under 2 meg of RAM required for that, uncompressed 16/44.1
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In the broader sense, I should think it unlikely to find any spinning disc CD player without some amount of data buffering.
If the disc could be spun so precisely to supply the bits continuously and unbuffered to the downstream devices, I'd be amazed