Is it worth upgrading a CD player?

My advice is the opposite of @kota1 .  The DAC is the most important part of a CD system.  If you have a DAC you like, then you are really just using the CD player as a CD transport, sending a digital signal to the DAC.

Streaming you are fighting bit losses as large files are sent over the internet.  I don't know for sure, and maybe someone who knows can speak up here, but I think CD players are much closer to "lossless".  If that is the case, there is not much to be gained.  

The key to digital is to get a DAC you like and it sounds like you have.  Once you have that DAC, I would never use the DAC in a cd player.

Jerry

@ghdprentice I think you misunderstood my post.  I meant that a streamer must work hard to deal with dropped bits and upgrading your streamer is key.  I have gone to an Innuos Zenith Mk3.  But I think the CD transport has much less tendancy to drop bits and thus any good solid well designed CD transport should get a good stream of bits to your DAC.  However, I am not sure about that and was hoping someone could confirm that CD transports drop very few bits.

Jerry