Best upgrade for cd player?

I thought you were looking to improve the player you had.  In that case, the Oppo 205 is a really good DAC. I had one - bought a Bryston BDA3 because it takes the DSD stream from the Oppo and I have a lot of SACDs, and honestly couldn't hear much difference between the two.  I think at this level you may want to figure out what kind of sound you want. IME the 205 is really transparent and detailed, perhaps can be a little bright.  In that same vein I liked the Lumin T2 better.  If you want warmer, perhaps the previous suggestions of tubed DACs. I moved on to a Marantz SA-10 and that was a good move towards smoother and more musical. But getting an outboard DAC is a great option, there are so many choices.

The Denafrips Venus ll should be a significant improvement in every parameter, or you can also probably do better on the cheap with a Gustard A22 or the new Soekris DAC2541.  Just a few to chew on, and best of luck. 

jimmy2615

Nice score! on the SA-10.  Happy Listening!

Why don't you let Modwright do it's thing on it?  Really, I had an Oppo for a while and never could get used to the CD sound.  They are going for such good prices, if you don't modify it, why don't you sell it and buy a better player? A friend of mine with very good ears replaced a Linn Klimax server with a Modwright 105 and much prefers it.  I didn't hear it myself. 

+1 on the Audiolab 6000cdt and a good DAC. Mine is paired with the Schiit Gungnir MB. The results have been very good.