"Note : (Bass) Improved over previous BC500 sound , not perfect .."
Have you ever had "perfect" bass in the listening room for reference?
This brings two things to mind.
1) bass is highly sensitive to speaker placement in room and room acoustics even with the best equipement
2) I had to adjust my speaker location somewhat when I switched in the BC amps. I find that switching amps in general typically involves at least some minor tweaking of speaker location within the room to retain best results.
I bought my BCs used and was not sure about break-in amount prior. At first, the sound was stark and bare sounding in comparison to my prior amp, a Musical Fidelity A3CR (Stereophile Class A FWIW). After a while, things settled in to a new and better reality. Part of this was my ears adjusting to the new sound, which was much tighter and cleaner and dynamic top to bottom still with very good detail. I attribute the different sound of the BCs somewhat to high damping factor (>1000 I believe is the spec). High damping is generally considered a desirable thing for my OHM speakers with the Walsh drivers. High Damping may not be the case with planars like Maggies.
I say that based partially on technical intuition but also on the fact that when I owned Maggies they worked well with a 360 w/ch carver m4.0t amp (low damping and current) whereas I had to dump the Carver to get balanced sound out of the newer OHMs.