You are in luck! As Palmerston, Curtis and Kal have noted , you can use the Tape Monitor, and the 2285b actually has two (2) sets (Tape 1 and 2). So you'll use the selector knob to choose AM, FM, Phono (1 & 2) or AUX, and then you would use the Tape 1 or 2 buttons to select up to two more line level sources such as CD, DVD, Tape Deck, etc. So why aren't thesee inputs selectable with the knob, just like the other sources?
In the olden days, when audio was ruled by Reel to Reel and Cassette (and the occasional 8-track and Elcaset), the Tape Monitor loops gave you the ability to select your source (say, Phono) and pass it out of the pre-amp section of the receiver to the tape deck for recording. If your deck had separate playback heads, it could then send the freshly recorded signal back to the pre-amp section via the Tape Monitor input. Hence, you could "monitor" the track that was being laid down on tape.
Plus, even when you weren't recording, you could still pass the signal through your deck so you could watch the VU meters dance. . . groovy, man!!
Anyway, since you're probably not taping, you can ignore the Tape Monitor Output and just use the Tape Monitor Inputs.