I assume you're trying to broadcast sound/music to people using the weight room (using headphones or equivalents)?
If that's the case, IMO you'll be better off with a low-power FM transmitter (one per source). Then folks can just bring / use their own FM radio/headphones to listen, and you don't have to worry about keeping track of equipment, damage, or cleaning it (ew!).
You'll see this sort of setup in many gyms / health clubs that have TVs positioned in front of the treadmills / cardio gear.