Ever demag a cart this way?

Firstly, check with your cartridge manufacturer before using this or any demag. technique. I have a Benz, and they said it was fine, so I use my fluxbuster to great advantage.

As Stringreen says, check with your cartridge manufacturer first. Quite a few (Van del Hul and ZYX for instance) will void your warranty if any active demagging has been done.

Cardas LP demag sweeps. Simple, harmless, cheap, effective.

Will and Test Record sweep that goes from 20-20,000hz deguass the cartridge (i.e Hi-Fi News Sweep), or does Cardas do something unique?

Yes, I've made various posts on the subject of cartridge fluxbusting over the years, to first the Analog Addicts mailing list, later the Phonogram list. Below is a link where a Phonogrammer archived one such post.

http://www.audioasylum.com/audio/vinyl/messages/61192.html

regards and hth

Thanks for the link and expert input, Jonathan!

Especially the warnings concerning Alnico magnets, which my XV-1s has. I'm going to try your suggestion of shorting channel outputs to grounds at the tonearm leads using a shorted pair of rca female jacks. I have the Cardas sweep LP to compare with.