Headphones vs Speakers

[DanP]

I'd like to report on my listening experience and ask if there is a scientific explanation.  I recently purchased a 5-year old SEX amp to demo with a set of the current single driver Omega speakers (Super 3T).  After running the speakers for 35+ hours, there was still very little deep bass.  I hooked up my headphones and heard plenty of bass.  I then connected the speakers to a 60 watt PP tube amp and the bottom end was much fuller than with the SEX amp leading me to conclude that the issue is not with the speakers.  Is there an electrical explanation as to why the amp can supply deep bass with headphones but not with a relatively efficient (94 dB) single driver speaker?  Is this a problem that could be overcome or improved by running the signal through a preamp or is this something that would only improve with significant upgrades to the amp?
Thanks,
Dan

[Paul Birkeland]

Hello Dan,

Yes, the original stereo SEX amp had some deep bass limitations that came primarily from the Speco output transformer.   This was greatly improved by the Magnequest output iron, and later by our own in-house designed pieces. 

When running headphones, the load impedance presented by the headphones is significantly higher than the average speaker, leading to better damping, lower power output (less taxing on the transformer) and a more present bottom end.

Both headphones and speakers will perform much better with the iron upgrade.

-PB