Why buy older digital gear?

Because it still reproduce very good sounding music. Old Cal Audio Tempest with 4x oversampling will surprise you with its pleasing sound, not associated with digital sound of that era. Or better yet, Linn Karik/Numerik combo, SFCD-1. I've been lucky to pick DPA 1028 DAC, circa 1984, and with my vintage Karik makes most 'analog' sound that i've heard from digital gear. I haven't listened SACD, or DVD-a yet, but those two formats aren't going anywere. Yet!

I have a krell 30i with no upgrades in one of my systems that I love listening to and its DAC is first rate for my 300 disc changer I also have hooked to it. I never think of it as old technology - just good sounding.

Listen to a Pioneer PD 65 again and see what you think.
tracer

...and because some brands still do old tech producing finest CD players such as BAT, Burmester, Cary.

Digital technology may have advanced as far as DAC chips go, but parts are still parts, and good parts and good design are still better than cheaper parts and a price point-compromised design. I'm sure many of the new sub $1000 players are great, but I bet a used CAl Audio, Muse, Theta, Goldmund, whatever...something that once cost $2500-$5000 new...is going to sound better than a $500 player with a current DAC chip. It may not have the resolution capability of the new DAC chips, but it should sound more natural, more transparent, have more bass, and smoother highs than a cheap player...all of the benefits that you normally get from a more expensive design and parts. I'm sure there are exceptions, but I bet most of the old hi-end CDPs and DACs that are selling for 1/10th - 1/3rd of their original retail are still a pretty decent upgrade for most people, and a good deal overall. They're certainly worth investigating if there are some in your budget range...especially in the $300-$700 range.