Is this for real?

Yes, it is typical of the "both sides". We have two people who have used the product and think it works, and two that haven't and think it doesn't. Now if someone wants to chime in who has used a product like this and think it doesn't work, I'm happy to accept that opinion too.

I've been using one I purchased about 6 years ago for about $15 with excellent results. Has a demagnetizing tone which I use about once a week, a burn in track (which I have used numerous times and works quite well), and a cleaning track (brushes actually on the disc), as well as a number of set-up tracks. Wouldn't be without it, but wouldn't pay $100 for one of these either.

The disc I have suggests that there is a build-up of residual magnetism within cables, circuit boards and copper wiring. That magnetism may also be present in spades, other connectors or solder for that matter; who knows? Sam Tellig, in a review of the Densen disc, suggested that excellent results were obtained with single ended tube gear, possibly as a result of demagnetizing the transformers. I don't know how it works and I don't really care. There will be a thousand engineers tell me that a power cord can't make a difference and I know that to be false. The fact is that the sweep tone tends to "clean things up" for lack of a better description. It is particularly noticeable, as Ljij suggests above, when it has not been used for some time. The effects are more subtle when using the sweep tone regularly (the disc I have suggests after every 30 hours of play-I use it about once a week), but they are indeed there. I don't need an engineer for that, and at $20 or so, this is not an outrageously expensive tweak. If it doesn't work for you, you're out $20. Bob Bundus alluded to this in a tweak thread a couple of weeks ago: if you don't have experience with something, why ridicule it? Obviously, from the way this thread has moved on, it is working for some people.

"Demagnetize" is the word used on the disc I own and the word used in the review that Sam Tellig used in a December/97 Stereophile article relating to what the Densen disc did. I'm not really the technical type, so if "demagnetize" is incorrect terminology, to me that's just semantics; the important thing is that it works.