The Audiolab 6000CDT has a nice felt type surround at the loading slot. So, unless you really try to put a CD in poorly aligned with the slot itself, no protective tape or similar should be needed.
I’ve had mine for a while, and although it was a concern for me, not really any longer. Just be careful, and if you remember to do so, take a micro fiber cloth to the CD and wipe it before inserting.