Can the HT-300 be connected to our loop system (for the hearing-impaired)?

There is nothing to stop you, but this would be a bad idea for those wearing hearing aids. A pipe or electronic organ, piano or worship band is not commonly connected to the loop system because the output level would usually be uncomfortably high. However, it is often possible to leave a microphone switched on in order to allow a small amount of sound into the loop amplifier.