I'd like to add, a note of caution. It is squarely within the purview of the FM group to provide a "Crab Box" or equivalent for each meetinghouse. One of the benefits to the wards and stakes of allowing them to do so, is that they are responsible for the care and maintenance of that equipment. If you or the ward, stake buy the equipment, that may be a violation of the policies in place, but also, places the burden of care and maintenance of that equipment on the purchasing individual/organization.
If you have not already, contact the FM about your needs/wants. Also be patient, and try to be clear about what the problem is. Most FMs are not technical, and will need a clear understanding in order to explain it to whomever they assign repairs/troubleshooting too.
Also, In the newest systems (last 10 years or so) the need for a crab box should be minimal as most rooms with systems include provisions to connect external (stereo mini, and/or RCA) source devices.
Steve Poulsen - Meetinghouse Facilities Technology Engineer