Redbook: only 1/4 of the master tape???

I agree with the above that it is nonsense to claim a 1:4 loss. I make own recordings of choral/orchestral music so I know the master tapes before they leave the studio for the CD fabrication. I often do comparisons of master and CD and with a real high end CD rig the results are very satisfying. The better the original recording/master the better the CD: so that 1:4 thing sounds to me like another attempt to push SACD or whatever format into a market which doesn't need it.

Redbook is 44,100 samples per second.

First of all, understand the performance being recorded literally has no sampling. Rather there is a continuous stream of music, lets call it infinite (zillions) of samples per second.

If the master tape is digital, recorded at a higher resolution than the early generation digital recorders, then the sampling rate might be 96K (~1/2) or 192K (~1/4) or 2.7M (DSD).

No matter what the master tape is, redbook has been and will continue to be a 44.1K media. So I ask, what does it matter what the original master resolution is as long as it is high enough to get 44.1K min onto the CD?

So the real question is not what the master was, it is what other formats than redbook CD will sound like if we can get that higher sampling rate to a different media such as SACD or DVD-A etc.

you would need an INFINITE sampling rate to have all the information from the master tape - not likely soon, for obvious reasons!

So what is the ratio of loss, if that's the right word, going from say, 96kHz to 44.1K on a redbook CD?

It's not just an issue of sample rate, you also have to consider word length. Redbook CD uses a 16 bit word whereas better quality digital recording and processing is done at 24 bit or higher. The sample rate conversion process usually entails the altering of both factors. Opinions differ but it's my experience that word length reduction is more noticeable than just a reduction in sample rate. There are different algorithms for accomplishing SRC and some are clearly more transparent than others. The amount and type of dithering also has a major influence. It's misleading to ask what is the ratio of loss in that the data reduction does not linearly correspond to what the ear hears. Depending on the type of music, the skill of the engineer and the choice of SRC processing the conversion from 96/24 to 44/16 can be very noticeable to barely perceptible. Roughly speaking it's of the magnitude of going from analog tape to vinyl.

You certainly don't need an infinite sampling rate to capture live music let alone what's contained on a first generation tape. In theory a 192kHz/32 bit recording should have 192dB dynamic range and be completely linear out 48kHz.