I have enhanced al least 10 pairs of speakers by now.
Though I only 'beolab-ed' about 3 pairs of speakers. The first ones I did was a pair of RL 60.2 for a friend of mine as he wasn't really satisfied anymore with the sound of them. (after 20 years you can expect some degration both in the crossover and the drivers....).
I like to inprove on existing things. As I see it, if something is no longer satisfying then it's either change it or improve it. Technology evolves and improves all the time, so why not take advantage of the improved pieces that are available? I don't find it degrading to the product (I know many will dissagree...). Don't forget even B&O does a mk1, mk2, mk3 etc .....
So I installed all new drivers with specs close to the existing. We tried several bass drivers as these seem to be hard to match in these speakers. Finally we settled for a good pair of boston accoustics (stripped from other speakers). Even with the same crossovers it sounded already better. After updating the crossovers ( a modified boston acoustics one) it really improved even more and sounded alot more alive with better nuances and enough detail.
After that (we kind of went crazy .....or was the beer?........) we build in an (actually really cheap.I think it was $20) 100 WATTS amp board (cutout in the back of the speaker for the cooling ribs). powerlink plug and auto-on switch with a led (so it switches on when his beocenter switches on). To further refine the sound we even build a small quick-fix equilizer board into it to boost the speakers somewhat. The sound now is really quite good. As we did one speaker and left the other untouched till the end, we could compare them easily...
As we did more of these amplified speakers, we got a bit better at it. Also the use of better materials does help. (The last ones I did have an actual pair of icepower amps) etc. The cona is to become one of these projects.
Thank you for your interest.