Not only does it have no warning, but it refers to the RCA jacks as Phono jacks. Oops!

The lack of warning is possibly an oops (do ordinary line-level components such as CD players carry such a warning?), but "phono jack" is the standard term for those things in the UK, even when not used for RIAA-biased inputs. (Eeeh, I remember the days when RIAA were mainly known for being useful to the audio consumer...)

Peter