The standard speakers are frankly, rubbish. I replaced my speakers here:
https://the75andztclub.co.uk/forum/s...d.php?t=299321
Three-way Pioneers in the front with Harmon Kardon tweeters in the upper door mounts, with a pair of bass response units with matching tweeters in the rear. The difference in sound is night & day.
I still have the Harmony unit which really is more than acceptable with the speaker upgrade but l have a Symphony to replace it which has recently been returned by Jules who fitted the SLE bass circuit to it for me. I haven't fitted it yet but Jules says it sounds fantastic. Apparently the Symphony is known for a fairly poor bass response (worse than the Harmony) which is why l bought the SLE circuit before l fitted the unit but l think you'll have a hard time getting one now as they appear to be discontinued. I bought mine a few years ago as it was always my plan to fit a Symphony on aesthetic grounds as much as the power increase.
You could do worse than try the bass speakers linked to in my thread. They're not expensive & they have impressed me. I'm looking forward to getting the Symphony installed to see how they perform with the upgraded circuitry of the unit.
EDIT:
https://www.ebay.co.uk/p/21034596865?iid=323568964921
Actually l paid a bit over a third of that price, reduced from Halfords as the packaging was shop-soiled, but they're very good units so the price isn't unreasonable for the difference they make.
EDIT 2: It's linking to a cheaper pair now. At £48 that's only twice what l paid.