My 2 cents...
Yes, you are ready for an upgrade. A lot has changed, and mostly for the better.
Your first task is to get the specs on the Altec's (power rating, impedance,etc.
Then you'll need to look for an amp that sounds good with your speakers.
I have no experience with Altec's so perhaps other members can recommend amps that work with that speaker.
One thing that should be considered are interconnects and speaker wire. And, yes, they do make a significant difference.
Once again, try to find other owners of your speakers to see what they find to have worked. It will help you narrow down the list. And, if it confuses you, please let us know, or PM.
Bob