Distance is not an issue as it was all wired by me and I did all manner of tests (continuity, bitrate, etc).

Did you use a genuine category-5 cable tester? Or did you just run some PC programs?

The fact that you wired it yourself actually makes me suspicious. Not to say that your wiring was bad or anything. But cat-5 cabling is pretty serious stuff, and there are some subtleties about wiring it that most laymen don't know. For instance, if you don't get the right wire pairs on the right pins, you can induce crosstalk which causes packet loss under heavy load. Which brings us to...

I can easily connect my laptop downstairs instead of EMPEG and have no trouble going out to the Internet, etc.

Yeah, but surfing the internet doesn't saturate the line, does it? An Empeg synch is probably the hardest work that wire is ever going to do. It's possible that the wiring could be the problem, and you just never "pushed" it until the Empeg came along.

Have you tested it with a shorter cable run? For instance, plugging it into the PC directly with a store-bought (not made-yourself) crossover cable? It's time to start eliminating failure points in the connection, and that's the first place to start.

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Tony Fabris