Need it? Nope. If you have bad power to your house, then a line conditioner would make more sense.
Some believe that a Linear Power Supply will provide better power and thus better sound, than using a switching Power Supply. For a computer that is not doing digital to analog conversion internally, which is what a Nucleus is, I don’t hear the difference. But, as long as you get a good properly rated supply, the only thing you’ll hurt is your pocket book to try it out.
However, keep in mind that even if you put a LPS with a Nucleus:
And, as someone else pointed out in the same thread, it makes more sense to make changes at the source rather than have LPS’s all around. See:
The thread to discuss Nucleus and Power Supplies is here: