Add an external DAC. Make my Oppo UDP-205 a true top player

I found the use of an Equitech 2Q  for isolation plus an MIT Oracle AC power cable made a nice difference. (I had them prior to picking up my near the end of the line 205-- a little pricey relative to the Oppo; but it shows the 205 has potential beyond what you get from standard ac power, by quite a bit.). I felt lucky to get my Oppo and continue to be highly pleased with DVD's and Bluray's and streaming from my cable provider. Going to move up to a Samsung 4K and kind of excited about that as well :)

While the Oppo might not outperform a really nice DAC or a dedicated SACD/CD player, one thing you might want to do is keep the player "on" for at least an hour before listening. Another thing is to use a good power conditioner. In my system it made a big difference and I like what I am hearing. Even Spotify played through Chromecast Audio through the Oppo's optical input sounds pretty neat.

andrei_nz Read your post w/great remembrance of the changes I experienced w/my Oppo 205 doing very similar changes you suggest. My base system (NPS 400 Counterpoint amp into Aerial 7b’s then, now 10mkII) was driven w/the 205 as source & pre-amp. My 1st upgrade was to use a Shunyata Delta NR PC for the 205 (beyond my Shunyata loom), which had some nice subtle changes.
By luck the Counterpoint had XLR inputs which the Oppo could drive, I added the base Bionics IC’s and it was glorious.
Experimenting internally w/the 205 I found the addition of the dampening material and a Bybee IQ over the power supply were nice upgrades. BUT Having been an old AQ Sorbo foot user for years, at the encouragement of my audio guru Duane @ Automated Lifestyles/Bettendorf I bought some StarSound Tech Brass feet and cups (the idea to drain energy out of chassis) WOW that made the 205 musical again. Am now looking into next step of DAC combo & like ideas various members have offered regarding outboard vs upgrade etc.

Oppomod transformer is said to give nice sonic improvement.
Cheap over the long run.

@dcaudio  -

With your budget, you could try a Naim nDAC combined with a Teddy Pardo TeddyXPS power supply.  Excellent sounding and very well built, both by companies with long excellent track records re service.  The pair would be under $2500.  The combination will see off any of the standalone DACs mentioned above. 

If you really wanted to go nuts and add streaming, you could do a used Naim NDS with the same Pardo TXPS; though an NDS would be $3-3.5K on its own (the Pardo TXPS is $1099 new) and requires a separate power supply.