The only portable cd player with a coaxial digital out that I know of was the Radio Shack CD3400, which unfortunately, is no longer made or sold. You may find one used, but I do not believe service is available for them anymore. They do sound good, even as a cd player.
What you may want to explore, if you have a portable cd player with halfway decent sound from its analog output; you could get an Art DI/O dac and use it to convert the analog to digital and then back to analog, upsampling to 24/96k. This would also enable to you to use the "tube warmth" feature of the DI/O. This would be a great toy, however, I am not sure whether the DI/O dac is better than your EAD. Also, my limited experience with a stock DI/O indicates it would not be my first choice for headphone listening due to its soundstage limitations.
What you may want to explore, if you have a portable cd player with halfway decent sound from its analog output; you could get an Art DI/O dac and use it to convert the analog to digital and then back to analog, upsampling to 24/96k. This would also enable to you to use the "tube warmth" feature of the DI/O. This would be a great toy, however, I am not sure whether the DI/O dac is better than your EAD. Also, my limited experience with a stock DI/O indicates it would not be my first choice for headphone listening due to its soundstage limitations.