Trevor, perhaps by the time you are ready for your dream system, a single driver speaker will be available that covers 80Hz to 20KHz. Otherwise, try to minimize the number of drivers and use a digital cross-over. Oh...and stay away from tubes, gramophones, reel-to-reel, cassette and 8-track smile.

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated