I cannot provide the answer to your question, however, I do not believe that the 'speed' or 'fast' actions of the transistors and/or high biasing automatically imply slam factor. Although these positive attributes would most certainly help to control and produce a well defined bass region even more than usual.
Even you stated that the Spectrals are known as a 'fast' amp yet lack that high slam-factor as you mentioned.
The Krell's and Levinsons are both known for a solid controlled bass, but I have never heard them known for their speed or being a 'fast' amplifier.
Fast has everything to do with reproducing the initial attack of a note and the ensuing decay of the same note which will also lead to more inter-transient silence between the notes giving the impression of perhaps a blacker background when in fact the listener is hearing more silence between the musical notes as the musician(s) intended.
Those amps lacking this speed will have difficulty reproducing the initial attack properly as well as the ensuing decay. And in the process subdue some of the micro- and macro-dynamics of the note. Even to the point where the notes appear to run together.
As one TAS reviewer asked in the course of a somewhat negative product review 'I wish somebody would explain why the tempo of one cdp appears slower than a competitor when in fact the tempo's of both cdp's are identical when compared to a metrinome'?
I may not be able to explain this very well, but to the best of my knowledge, this is exactly why.
-IMO
Even you stated that the Spectrals are known as a 'fast' amp yet lack that high slam-factor as you mentioned.
The Krell's and Levinsons are both known for a solid controlled bass, but I have never heard them known for their speed or being a 'fast' amplifier.
Fast has everything to do with reproducing the initial attack of a note and the ensuing decay of the same note which will also lead to more inter-transient silence between the notes giving the impression of perhaps a blacker background when in fact the listener is hearing more silence between the musical notes as the musician(s) intended.
Those amps lacking this speed will have difficulty reproducing the initial attack properly as well as the ensuing decay. And in the process subdue some of the micro- and macro-dynamics of the note. Even to the point where the notes appear to run together.
As one TAS reviewer asked in the course of a somewhat negative product review 'I wish somebody would explain why the tempo of one cdp appears slower than a competitor when in fact the tempo's of both cdp's are identical when compared to a metrinome'?
I may not be able to explain this very well, but to the best of my knowledge, this is exactly why.
-IMO