Anyone ever try something like this?

https://audioxpress.com/files/attachment/2685

I wanted to see if I could find something passive that would take an unbalanced signal  from a preamp and convert it o a balanced output.  Is this worth trying?  Or would I damage the balanced amp?

There are plenty of commercial products (and DIY for that matter) that take a line-level signal and use passive components to create a differential signal.  My first thought would be that if you're going to do that, it'd be something I'd argue is worth spending some serious $ on.  

I agree, I've found a few schematics online similar to the one I posted above.  I see that edcor makes a similar one for $28  https://edcorusa.com/products/copy-of-pc-series-balanced-or-unbalanced-line-matching-transformers?variant=41110251962555

I think I'll order a pair just to see how it works.  The Jensen transformers are $95 each.  I also found https://cinemag.biz/line_input/line_input.php

Do you think I'm fine with 600 Ohm | 600 Ohm like the article?  The input would come from the lineout of a chord mojo and feed a Dynalo mini

https://www.jensen-transformers.com/application-notes/

that's some good reading.  I didn't see that.  Thanks

Look up the Neutrik NA2 MD-0B-TX and Neutrik NA2 M-D2B-TX for this and enjoy.

They are the same except for the black/red color on the chinch. 

Thanks, I'll take a look

They have mini transformers build in and are just excellent (and very handy).