Still I have some doubt if best sound can be achieved by CD player only... Any other method to get the best of digital files like now a days we have steamers, media players, Bluetooth/USB DAC etc. Anybody has any idea about that?
For Any intended Improvement in Sound quality go by RSS way ( most of it is available in detail on YouTube self help videos)
R - room acoustics, basic thick center mat, absorption at first reflection point, seating arrangements etc
S - speakers positioning, distance from sidewalls, distance between speakers, isolation, towing angle etc check your speaker manual. Getting right stereo imaging etc
S - Sources optimization & Synergy , pure Power Supply, Stabilizer for HT room sockets etc
Assuming you're through with the basic requirements for best possible SQ at your place in your budget,
Let's move on to the source discussion
Good Source files ( you already have ripped Wav files), Now get a Source player which can extract maximum information from your looseless files, a DAC which converts maximum source player retrieved information into the best possible analog output without losing the details. I don't think your Sony DVD player is designed for getting an audiophile quality by any means. Information retrieving ability of your source and its DAC will be the weakest link in your chain. I think u need to move beyond sticking to any DVD player for audio SQ.
A good media player and streamer with decent in built DAC will cost you more than 25k onwards. Some say 60k onwards but it depends upon everyone's experience and budget.
My suggestions for your budget would be to get DAC + Media Player + Streamer option like Yamaha Wxc50 at 25k instead of Marantz CD 5005. If you can drop the idea of Streaming option and want a CD player, better buy will be Marantz CD 6006 at 37k, with USB flash drive support for your ripped Wav files. By the way, don't bank too much on Wav files downloaded from Saregama, they're poorly mastered and you should instead use the Cds or your own ripped Wav files.