I thought people here would be interested in this PDF from Philips.
On page 10 it shows the specs for the TDA1541A, TDA1541A/R1, TDA1541A/S1 and TDA1541A/S2 side by side. It's interesting to note that the TDA1543 is listed as "economy" while the 1541A is classified as "high-performance"....
http://www.semiconductors.philips.com/acrobat_download/various/DIGITAL.pdf
On page 10 it shows the specs for the TDA1541A, TDA1541A/R1, TDA1541A/S1 and TDA1541A/S2 side by side. It's interesting to note that the TDA1543 is listed as "economy" while the 1541A is classified as "high-performance"....
http://www.semiconductors.philips.com/acrobat_download/various/DIGITAL.pdf