Hi monk,
The Dynaco speakers are fairly neutral, so they should be okay. If memory serves, the ADC's are not neutral (I think they used German drivers from Braun).
When you mix brands with various tonal "character", you will notice differences in coloration, and the overall integration of the 5.1 channels won't be as successful as it would be with Axioms all-around. But it will likely be ok for awhile until your start finding the coloration and inaccuracies annoying.
In the early days of Dolby Surround (pre Pro Logic, pre digital), I recall using a portable powered center speaker from Bose as a center. It was convenient but horribly colored, especially with dialog voices. Eventually, I took it out and did without a center until I could get something better.
Regards,
