A bit more detail:
At the same time as replacing those 4 foam pads on the side walls of the top cabinets, I also tightened the spikes on my left SL2 and corrected the leveling on that speaker - so that will also have improved clarity of sound.
One other factor is that I had removed the crumbling foam from that left speaker a couple of weeks ago and so it sounded thinner and slightly more out of focus since then.
So the change today got rid of that bald left speaker SQ and it got rid of the right speaker with crumbled foam in it.
And replaced both with a matched pair of well damped top cabinets - i.e. the crucial part where the magic mainly happens.
Anyway, in a nutshell, my advice to SL2 owners is - check those foam pads and replace if they are not perfect.
They are not glued in, so come out very easily.
Just get some acoustic foam and cut to size.
The sizes and details are in the other thread linked to above.
I got foam from efoam {.co. uk}
Others used PureSoundSales on t’Bay, or other foam suppliers - see other thread for details.
In case anyone thinks I’m exaggerating, the other thread contains quotes from other people who replaced the foam in their SL2 top cabinets and said things like:
“Highly recommended, they really rejuvenated my SL2s.”
And: “I’ve now fitted the dampening foam to my SL2s. I wasn’t expecting to hear much difference but I’m pleasantly surprised. The top end sounds much smoother.”