Jitter reduction, best device?

I'm not sure how audiophiles can diagnose a jitter problem except by trying jitter reduction devices and listening. In general, upsampling DAC's will be more immune to jitter because they re-clock the signal to a higher rate. The re-clocking will filter out a lot of the jitter in the original signal. I haven't seen any way to measure jitter except for using expensive lab equipment.

There is a renewed interest in jitter because of the new PC-based servers. The data from a hard drive is read in blocks without an inherent clock. An SPDIF clock is generated at the same time that the SPDIF data is created. It's this clock that has the troublesome jitter. Most PC manufacturers and even sound card manufacturers don't care that much about jitter. It's only a few audiophile nuts like us who are concerned about it.

I'd like to see SPDIF jitter measurements standardized and published for PC's and PC soundcards that output SPDIF signals. Then we could really tell how bad the jitter was and whether we need outboard jitter reduction. (The SPDIF signal is what goes between the PC and the DAC, either in optical or coax cable)