You can rip DVD-A and Blu Ray directly to digital. However, you need an original Play Station to rip the SACD. At 24/192 you will probably get audio pretty much equivalent to what your hear from your existing player. The advantage of ripping the digital data is that it is not in any way changed by the D to A conversion in the player. There is a program called DVD Audio Extractor that will take the data directly from the DVD-A and Blu Ray and covert it to flac. I would try that first. They have a 30 day trial and the software is inexpensive. It should be much faster and better quality than digitizing the analog. IF you want to try upscaling the results to a higher sample rate you can do that after you have ripped them. For SACD, the Tascam is probably a good way to go.
In general, DVD-A and SACD should be better quality than the CDs. Not sure about the Blu Ray (not much experience) but hopefully they have more dynamic range that current CDs. HD downloads are a crap shoot. Many are very good especially if they have been re-mastered or were originally done in a hi-rez format. The Sony SACDs downloads (Acoustic Sounds) should be identical to the SACDs. You might see if you can compare one of your SACD digitized files with the SACD download. If you extract the DVD-A and Blu Ray files, the only difference between those and the HD downloads should be the mastering, at least at the same sample rate.
I am currently digitizing a lot of vinyl with a Korg MS-2000 A to D and the results are very close to the originals. The Tascam is in a similar league (although I think the Korg is better, but what owner doesn't think that) so I would expect you will be able to be pretty close to your original analog source. That should be an easy test.
If you want to go further, Busman Audio will upgrade the input stages of the Tascam for not a lot of money.
My advice - rip the DVD-A and Blu Ray and digitize the SACD.
In general, DVD-A and SACD should be better quality than the CDs. Not sure about the Blu Ray (not much experience) but hopefully they have more dynamic range that current CDs. HD downloads are a crap shoot. Many are very good especially if they have been re-mastered or were originally done in a hi-rez format. The Sony SACDs downloads (Acoustic Sounds) should be identical to the SACDs. You might see if you can compare one of your SACD digitized files with the SACD download. If you extract the DVD-A and Blu Ray files, the only difference between those and the HD downloads should be the mastering, at least at the same sample rate.
I am currently digitizing a lot of vinyl with a Korg MS-2000 A to D and the results are very close to the originals. The Tascam is in a similar league (although I think the Korg is better, but what owner doesn't think that) so I would expect you will be able to be pretty close to your original analog source. That should be an easy test.
If you want to go further, Busman Audio will upgrade the input stages of the Tascam for not a lot of money.
My advice - rip the DVD-A and Blu Ray and digitize the SACD.