I also have the DVP-NS999es DVD/SACD/CD player. The analog output stage (in the US version, other parts of the world get better opamps, according to the factory service manual) uses some pretty cheap opamps. I replaced them (and installed sockets) with better opamps. The Analog Devices AD826 or the Burr-Brown (owned by Texas Instruments) OP2132 are noticeable improvments!!!

I use the Sony TA-P9000ES to do various switching functions between the 999ES, SCD-XA77ES and a couple of other sources. Following the TA-P9000ES, I have an ICBM for bass management and active crossover function for my speakers and subwoofer. Bass management in my other pieces of equipment is not used.