Amp upgrade / Did Classe go out of business

From what I have read, they are either out or soon going out of business.  Thats what happens when a small company gets bought out by a large conglomerate.

do you think that I should not buy a used Classe amp because of that

I think you buy a new one from a dealer at cost. If I was a dealer, I would be thrilled to turn merchandise with no warranty of manufacture support in to cash. Maybe even less than cost, but beware as you have no post sale support. 

As someone who owns equipment from a defunct manufacturer, you should think long and hard about Classe.  Whether you own it short or long term you're incurring considerable risk, so unless there are no close alternatives I'd advise you to pass on Classe.  I can tell you it's an uncomfortable way to live -- always fearing something going wrong.  And this is obviously not a cheap purchase.  Anyway, hope this helps and best of luck.