DK Design VS.1 Reference mkII - Optimization

I would like to know what tuning, customizing, hot rodding, tweaking, what ever.. that you owners of DK Design VS-1 MK2 are using to bring out the best in this amp. It seems to be responsive to changes in interconnects, tubes, power & speaker cables, speaker dynamics, etc. most probably to both the positive and negative.

Please share your work. I would like to know what improved it's performance, what caused no real change and what made it sound worse. Thanks in advance!