How do you know if you are upgrading your DAC?

The OPs question might as well apply to any component in the chain. 

I had a 205 and never thought much of its CD playback.  But I will tell you that putting a Vibrapod 3 under each foot made a considerable improvement.  I never thought Vibrapods did much until I tried it under the Oppo.  Another user here said his 105 improved quite a bit when he put some brand of spring footer under the unit as well.  IMO, any of the dacs mentioned here are far superior to the Oppo, but that is no guarantee you will hear the difference in your system with your ears. I now use a Heed Abacus dac and it is miles ahead of the Oppo, IMO.  No comparison.  But do try the Vibrapods. Really. 

It's an upgrade if you like it better than what you have

It's an upgrade if you like it better than what you have

top post of 2020!!!!!!!!!!!!  bravo...  :)

You can try an Audio Mirror Tubadour SE Mklll in your system and send it back if it’s not an improvement.  My bet is the 205 will be sent to the trash instead.