It is not easy to say something for certain at this stage. It is not worse with those devices in place, I can say that. But if they make for a substantial improvement, compared to without, is harder to say as there weren't any loud irritating rattling before they were installed. As they cannot be taken away instantly, sound memory is generally short and it wouldn't be a blind test, this too makes it harder for quick dependabale comparisons. Also, as the wife is home I cannot play at very loud levels where differences could be more noticable.

My imagination is of course 100% positively certain though . Placebo can be a potent medicin!

(It think it might be easier to determine after some prolonged listening with and without them.)