Cwazz,
What is the damping factor of the amps you used? This can really affect the bass extension. As I mentioned above, I have found that low damping factor amps play very well with full range drivers in ported boxes, as long as they don't lead to the driver becoming underdamped, which would lead to loose and sloppy bass.
It may not be a case of tube vs. solid state, or something that a more powerful amp will fix. I've run my speakers happily with 5W-10W solid state amps (FirstWatt F1 and F2j) with low damping factor with great success. Very satisfying bass. And my Atma-sphere S-30 at 30W also delivers, but I think this again is more due to the low damping factor. Aleph 30, SS design providing 30W by the same designer of the F1 and F2J (Nelson Pass) did not work as well, due largely to the high damping factor which led to my speakers being overdamped. FWIW