Update: So I started fooling around with the attenuator knob on the 8256s. It is quite a useful device. Having had a frame of reference of trying to get as much high end as possible, I had the knob almost all the way up, like on my Heathkits. After listening to lots of different music for the past couple of days I was feeling disappointed in the bass response. Well...that little knob took care of that. I now have the MF, HF/MF button pushed in to attenuate just the mids and have it now almost all the way down. The highs are retained and mids tempered several dB so as to let the bass really shine. It became actually too much and I turned the mids back up a tweak. It now sounds very balanced with buckets of slam and no shortage of those wonderful Altec mids. My 15W amp is still more than enough to shake the windows. Now I have to work my way through the library again...

BTW, I spoke with Bill today and the 515Bs are soon to be off for recones.