You could upgrade your dac to a much higher end dac, and with a really good streamer you would hardly want to play a CD.
I have to agree with
@audiotroy as having a good streamer seems to be the way of the future, and I would trust their advice on good streamers as I'm sure they've heard many. As another option if you still want to spin the occasional disc, you could upgrade to a better DAC and invest in a good jitter reduction unit such as the Empirical Audio Offramp and continue to use your Oppo as a transport. The Offramp makes any transport a great transport, and you can keep using the Oppo. I hate trashing stuff and love repurposing older gear if it still works -- but that's just me.
For a new DAC, it's such a personal decision. But there's a resurgence of non oversampling R2R ladder DACs out there that are garnering a lot of attention as sounding more "natural" and "organic" versus the upsampling single-bit DACs that have dominated the digital landscape over the past decade or so. The Metrum Pavane has gotten sparkling reviews among others, and there's a lesser-known manufacturer that makes the SW1X DAC that seems most impressive and offers a free trial period (minus shipping) that would very much be worth a look. Gotta love an in-home trial!!! Hope this helps, and best of luck in your search.