Sonnet may have wised up and built termination into their boards, after all the grief Newertech encountered. It still sounds like a valid troubleshooting experiment ... if you can find the said PDS terminator, that is.

Fastest Sonnet Crescendo Nubus was 500MHz - their 1GHz upgrades were for PCI machines and later.

And a small correction to my earlier blatherings above, it was the Crescendo that I recalled having the socketed passthrough, and not any of the Newertech ones.