Yes, your CD player has a compliment of digital inputs on the back, so you can use it as a DAC. You could attach a streamer and a transport. I recommend not using the optical, they tend not to be as good.
Transports within CD players tend to be unreliable. You might verify with Krell if they can repair it. Typically companies lay in a lot of transports for repair… but it is pretty old.
I’ll let someone familiar with transports make a specific recommendations. I would like to mention that streamers are like any other component… like a turn table, the better you get, the better you will hear. I would put my money into a good streamer as CDs are really on the way out and a good streamer will provide all the music you already own times thousands for $14.99 / month (Qobuz streaming recommended). Streaming can exceed the sound quality of a red book CD. Unfortunately, it is important to match the quality of the streamer to your system, and a $1,000 streamer is unlikely to come close to the quality of the rest of your system. Although you can certainly get one for that cost. If you budget is a hard number, this would be the way to go. It might lead you to later upgrades.