Even the original 14 bit 4x oversampling Philips CD100 (also sold as the Marantz CD63) was transparent.
Well... these early digital filters (SAA7030) are a bit of a mixed bag.
On the one hand, they are quite tolerant to intersample-overs and very clever bits of engineering for the time (I mean, they're using dither with noise shaping, this is how they were able to get performance that's arguably even a bit past 16 bits out of 14-bit DACs, at least in a 20 kHz bandwidth).
On the other hand, they have almost ±0.2 dB worth of periodic filter ripple in an FIR filter. Julian Dunn would have a heart attack if he wasn't already dead. I've had issues with "wonky treble" on something with ±0.05 dB, so would have my doubts in this area. I suppose the designers were going off of what was common for analog (IIR) filters at the time. They couldn't have known about any issues associated with pre-echo.
Fundamentally, even the early NOS jobs were not bad to begin with. They needed some crutches like external S&H and deglitching that didn't make distortion performance any better, not to mention the 13th-order integrated Bessel lowpass (possibly ceramic?).
Things got interesting once the Japanese had caught up to 4X oversampling around 1986, and by 1987 we saw the first high-performance digital filters like the Sony CXD1088 (periodic ripple below ±0.001/0.004 dB). Which has little headroom for overs but that wasn't too much of an issue with material available at the time. That one seems to have been combined with the TDA1541(A) a lot (even in Sony's own players!), less often with the PCM56P. I wonder why, I'd think that the trimmable PCM56 would fare better for low-level linearity (but perhaps not untrimmed, accurate trimming also seems to be a bit
tricky).
By 1990 we had arguably moved past CD-level performance already... a well-trimmed PCM63P-K does in fact make it to 20-bit linearity, and NPC SM5803 and SM5813 8X oversampling digital filters boasted periodic ripple below ±0.00005 dB and a -110 dB stopband (even though they still limited overs and the digital volume was placed on the output side
after the filter).
I wouldn't know what to improve about
this one. It's not even bothered by overs. 1992.
Now, the less said about the late-90s to early-2000s fad of putting ASRCs for upsampling into CD players the better. This happened at the exact same time that mastering levels went through the roof and overs became commonplace.
D'oh.