How To Clean Piano Black Speaker Finish?

Any of the reputable products for car finishes should be fine, I mean these aren’t outside, exposed to elements etc... I suppose though if they’re by a window getting direct sunlight one should take the proper actions/maintenance.

If your finish is in good shape (no swirls, deep scratches), really not that difficult.  Dust and use a good quick detailer for fingerprints/gen cleaning and then use a good wax or sealant and that will make all subsequent cleanings (e.g dusting) a piece of cake.

Mequiars Ultimate Quick detailer is a great and readily available product along with their waxes.

One key component regardless of what product is used, MAKE sure microfiber cloth is clean and free of any contaminates. Use one for cleaning and one for polishing 

Best way to keep piano finishes looking great is to not contaminate them with fingerprints or other contaminants in the first place. Your speaker finish will never need more than a dusting if you are careful. Whenever I have to move my speakers (which is hardly ever), I put on the white gloves that came with my Prima Luna preamp. This avoids getting fingerprints on the finish. You can use something similar. After that, only a light pass with a feather duster keeps my Tritons looking brand new.

J.Chip

I agree with J. Chip. My Zu Def 4s in piano black are 8+ years old. Rare gentle dusting. White gloves or a cloth when moving - again rare. Avoid fingerprints. Don't touch the bare surface. Etc. They still look new.

I’ve used Windex and paper towels on my NHT
VT 2’s for 18 years. No scratches  at all