It's been about 10 days since I placed a total of twelve Stillpoints Ultra 5's under my power amp which is dual mono, dual power supply. I placed three under each amp and another three under each power supply. Recently, at THE Show in Newport, I spoke to Bruce Jacobs as to his recommendations as to where to place these Ultra 5's. It was his suggestion to try one under each transformer. If I were to do that, I would need five Ultra 5's under each power supply as there are four rear transformers and I placed another Ultra 5 towards the underside of the front centre part of the amp. However, I only had three for each power supply such that I placed two under each of the two rear most transformers and the third under the front centre. I thought this sounded wonderful.
Bruce however, as well as just about everyone here who uses Stillpoints, always says to experiment with placement because each change and they produce a different sound. This afternoon, I pushed the Ultra 5's that were under the front centre of each power supply back approximately six inches such that they now sit under the junction between the two other transformers. Bruce had suggested ideally to have one under each transformer but failing that, he suggested placing them under the seam where the transformers meet (which is what I was able to do without the amp falling forward due to this third Ultra 5 being too far back of centre) Presently, there is no shift in the balance of each power supply but I was stunned at the change in sound. These devices are truly remarkable and I would recommend people consider them. The improvement for my ears is always better in the deep bass and low mid bass, however the entire midrange seems to sound so much better.
My only other option is to use five Ultra 5's under each power supply but these things are far from inexpensive.