It's glue - used to hold the components in place while wave- or hotair soldering.
It's not easy to remove the IC.
Cutting the pins, breaking off the chip and cleaning off the glue, there's a huge risk that the board traces will come off.

But replacing the OpAmps will not give any improvement to speak of.
Many other aspects will have to be addressed before you can hear any improvement - and still there would be a long way to a result
that could be called audiophile.

Many before you dreamt that they could make elegant speakers like these sound fantastic, but Beolab 8000 won't ever
do that, and it won't be audiophile.
- Not by replacing electronics anyways.

Another thing is, that modifications to B&O units often affects value at a sale.
What in your opinion was an upgrade could for others be a step in the wrong direction.
I have had several B&O units on the bench, that owners wanted returned to original.
Units messed with drops in value like a stone. Keep that in mind if you plan to sell them at some point.

I suggest you leave the Beolab 8000s original, enjoy them as they are or sell them and Buy Beolab 90 if you want
something sounding closer to the real thing.

Martin

good points, Dillen

I asked Geoff about opamp modding and he wrote me:

Op amps are certainly different - but there is no way to generalize them. This is because they differ in their distortion and frequency response characteristics with gain. This means that a TL072 might be “worse” (for your tastes) than a 2134 for one application - but the reverse might be true for another application.