Originally Posted by maxnix
RIAA as I understand it is an electronic analog phonograph equalization so that low frequencies did not require analogously great topographic differences for lower frequencies.
The RIAA is not an equalization curve.
The RIAA is an association. Over their decades long existence they have endorsed and supported many measures to benefit the recording industry. Their scope of their membership has caused many of those initiatives to become de facto standards. The phono equalization curve to which I believe you are referring was just one of those many 'standards'. In fact this standard was an amalgamation of many in place at individual studios and pressing plants over the years. Examples would include:
Columbia-78, Decca-U.S., European (various), Victor-78 (various), Associated, BBC, NAB, Orthacoustic, World, Columbia LP, FFRR-78 and microgroove, and AES.
The RIAA lives on today and has in place various algorithms, curves etc for digital recording. Many people are under the misunderstanding that digital recording is a matter of WYIIWYO (what you input is what you output). Although the digital audio format is capable of that, due to the many codecs and variations of media and intended playback situations several parameters must still be controlled. Whether it's dithering in the top end - the blain of SACD or merely rolling off the low end so as to not damage low typical low frequency transducers - there are a lot of things at play.