Lucky for you - pretty much any DAC in recent years will better those old players. Take your pick - Stereophile has a Class A and A+ list. Benchmark, Mytek, Bricasti, Bryston, Ayre, Chord and Weiss...are places to start. All are excellent although features/budget/aesthetics may govern your choice. There is no day and night difference between these DACs but they will make you regret having kept your existing players with their decades old technology for so long.
If you are particularly concerned about incoming jitter then Benchmark and Weiss reject it entirely. Jitter rejection has been a key development since your old players. Also the Benchmark handles intersample overs without the typical DAC distortion seen in every other DAC (If you listen to pop/rock CD then intersample clipping is on almost everything and creates harsh distortion)
For as little as $2000 spend you can be leaps and bounds ahead with a brand new DAC and continue to use your existing transport as a player or switch to digital computer based music files like everyone else.
If you are particularly concerned about incoming jitter then Benchmark and Weiss reject it entirely. Jitter rejection has been a key development since your old players. Also the Benchmark handles intersample overs without the typical DAC distortion seen in every other DAC (If you listen to pop/rock CD then intersample clipping is on almost everything and creates harsh distortion)
For as little as $2000 spend you can be leaps and bounds ahead with a brand new DAC and continue to use your existing transport as a player or switch to digital computer based music files like everyone else.