Best way to clean glossy finish on speakers?

I do not know the answer to your question but I have some very glossy black speakers from Yamaha (same finish as their pianos). I am looking for best way to clean them my self. 

One thing I did for both a dust and safety issue was to get a cover for them.

YAMAHA NS-5000 Dust Cover (digitaldeckcovers.com)

Dont use alcohol!!

If you find anything stuck, Goo Gone works well.

Dust lightly with a clean swiffer

I use a spray intended for cleaning Apple Mac screens. Otherwise, just dry dust, using mop type duster or Swiffer. 

Use a swifter and never touch it. Almost any cloth will have dust embedded in it and will cause micro scratches… dulling the finish. If you had accidentally touched it, then use a brand new / perfectly clean fluffy micro fiber closet with a small mist of water on the cloth.

Once clean, don’t touch and dust with a swifter.

It most beautiful finished items I owned are my Sonus Faber Amati in red violin… they are simple mesmerizing to look at. I want to do nothing to take away from the finish.

I would think caring for a Steinway piano would be the same for your speakers. 😊

https://www.steinway.com/news/features/utilty/cleaning-your-piano