I've been very confused just by the audio-related part of this thread. If I understand correctly:
- The original poster (OP) has a turntable in his living room and a Yamaha cxa5100 AV preamp in another room.
- All his speakers are self-powered; they contain internal amps.
- Presently the OP runs long XLR cables between the AV preamp and the speakers.
- He wants to add an external phono preamp between his phonograph and his AV preamp.
- His AV preamp does have an internal phono preamp, but it requires a short RCA cable run, no more than 4 feet (1 meter) long between the phonograph and the AV preamp.
- Finally he wants to find an external phono preamp with XLR inputs and outputs.
If I recall correctly, a phono pickup cartridge is an unbalanced device. There is no need for or benefit from using balanced XLR cables to connect it to a phono preamp. For the same reason, there is no need for or benefit from using XLR cables between a phono preamp and his Yamaha AV preamp. There are many external phono preamps, with RCA jacks, that will allow the OP to place his phonograph further than 4 feet away from his AV preamp. Many of them cost quite a bit less than $1,000. I don't see any reason why that wouldn't work well for the OP.
I don't have anything to add about the non-audio parts of this thread. I do agree that the original poster may be wrong about the danger of electromagnetic fields. I also understand that the life-threatening nature of his heart disease may have influenced his thinking and led him to some very unusual conclusions. As a result, I doubt anything we say here will change his mind.