Using a condom does reduce sensation, so I'd prefer to do it without one if possible.
Literal
Condom [object-を] use [conditional-と] certainly sensation [subject-が] drops [because-ので], if-possible raw [with-で] want-to-do.
A frank sentence about sexual preferences. ゴム (rubber) is colloquial for condom. 生 (raw/bare) is the slang term for unprotected. 確かに (certainly/admittedly) concedes the point. ~ので links cause and preference. できれば (if possible) softens the wish.