1. Direct cable link as you suggest. Need to buy some inexpensive kit.
2. Split the files onto floppy disks with Chainsaw (104K) click here Splits large files for easier transfer and recombines them with a batch file.
3. Take the hard drive out of one base unit and connect it into the other as a slave drive.
4. Send by email
2 and 4 will be easier if you convert the *.wav files to MP3 first.