Berlin Visitor Advice: Best clubs for BDSM and swapping?

Hi, we are a couple from England visiting Berlin in June. This is our second visit and last time we visited Insomnia which was our first experience of a sex club, we loved it. We both swapped and also enjoyed some gentle BDSM. This time we would like to expand our experience of swapping and BDSM. We arrive on a Wednesday and are staying for a week.
We would appreciate any advice or the best places to visit and when.
Thanks in advance and hopefully we will see you in a club during our visit...xx
Julie and John