Unfortunately, that is not quite the case. Most of the older players skipped all too easily when you listen to your CDs during walking, and those that had any kind of anti-skip circuitry in that generation actually provided 3 or 10 seconds of REALLY compressed, REALLY lossy anti-skip! And that's because memory buffers (the ones used as anti-skip buffers) were ASTRONOMICALLY expensive in those days (i.e. when the first Electronic Skip Protection PCDPs came out, 1MB of 8-bit FPM DRAM cost a whopping $80 back then
, versus about $25 for 256MB of PC133 SDRAM or DDR266/PC2100 DDR SDRAM today). So the PCDP manufacturers used an EXTREMELY puny amount (in bytes) of memory in those early digital anti-skip players.
Today, that situation isn't much better - sure, a few PCDPs, such as many models in Sony's G-Protection line, have a relatively LARGE (in bytes) amount of memory buffer (because memory is so cheap nowadays), so that some manufacturers can claim as much as 10 or even 20 seconds of UNCOMPRESSED anti-skip. But something's got to give: In an ongoing effort to improve battery life, the sound quality at the headphone jack suffers - and often GREATLY. Worse, many of those headphone jacks can BARELY drive the REALLY crappy headphones that come bundled with the players, let alone GOOD hi-fi headphones. And as I have seen, even the once-mighty Panasonic has eliminated the line-out jack on all but its top-of-the-line PCDPs. (Sony still has a line-out jack, but now you'll have to buy G-Protection just to get a line-out jack.)
Oh, BTW, anti-skip was virtually unheard of in the days of the Sony D-25S - I wouldn't buy that PCDP at any price, IMHO; you'd be WAY better off buying an AC-powered home CDP. What good is "portable" if you can't listen to your music while you walk? (There were a few "anti-shock" PCDPs that relied on mechanical "oil-damping" on the market when the D-25S was available, but in practice such "anti-shock" mechanisms only worked in the car, not for walking.)
Hope this helps.