Should one put a memory foam mattress topper  (1") on top of (or underneath) a quilted mattress cover.

Most would say that a memo foam topper should be under a protector, but a stretchy one like Protec A Bed or Southern Textiles Platinum is better than a traditional pad, because it stretches, allowing the topper to do its job. Now, a 1" topper won't sink much, any way. Also, all foam is sensitive to UV, so it needs to be covered. I guess a fitted sheet could do the job, though.