The Mac Solid State amps use an autoformer as a coupling device. I always felt it slowed and softened the music somewhat. That might explain your dissatisfaction with the sound from the 2505. Without getting into a long equipment list allow me to humbly state that I use the same 846B's you do and I did try them with the mac once. Great combo. There are many who say the drivers in the Altecs need to be re-magnetised and the crossover caps replaced. I don't notice any difference with those speakers that have had that done. I would suspect that your stuff sounds just fine and would not benefit much from a lot of changes. The only thing I would offer is raising my 846B's about 6" gave me a lot more high's and better definition and prescence. Also seperating them from the stuff around them would help.If you want you could try the speakers one at a time and listen to see if there is any difference. That might tell you if they need attention.
When was the last time you changed out the tubes on the Mac?