I've just spent some time reading the whole 16 pages of this thread & honestly I can't believe what is happening here.
You don't really expect high end, detailed, classic speakers to sound correctly by connecting them to 20 yo Cd players & non descript electronics.

You need to go back to basics here. Double check all your cabinet joints (I seal all the joints in my cabinets with a bead of silicone, regardless of who made them). Your cabinets appear to be very well made & I can't imagine they are contributing to the problems you are having, although I am a little dubious of the downward firing port.

It doesn't matter what your previous speakers sounded like with your current electronics, these Altecs will sound totally different with them.

Beg, borrow or steal some decent electronics, cables & source & you could end up saving yourself a whole lot of heartache.....not that you haven't gone through that already.

And whoever told you that your 20yo Cd player can't affect the sound....don't take any more advice from them.

Sorry to be so blatantly harsh here, but it really riles me that due to others advice you've been through this escapade & nearly sold a classic pair of speakers.
Please, please give them a fair chance to perform.
Remember....garbage in...garbage out.

Good luck.