Cleaning, polishing Speaker Cabinets ?

Different veneers and finishes require different methods. Some are finished so they can breath and some aren't. If your finish is supposed to breath, you must be careful because oiling it or applying pledge or wax etc. can clog the pores and now you could be creating a situation where you could damage over time to that finish depending on environmental conditions. Harbeth for example does not recommend oils for this reason.

If you have a finish on it, some waxes contain abrasives and over time, you could be wearing it down. I've seen Spendor say that the lacquer on their veneers should not be cleaned with polishes for this very reason.

Best thing to do is to ask the builder of your speaker. Hopefully they are familiar with what works best with their finish.

I purchase Coconut oil from Costco, and found it to be excellent as a wood polisher/conditioner.

Plus it smells like you're at the beach, right?

Novus plastic cleaner (comes in 3 intensities for various scratch removal needs) is what pro guitar repair people (Pat DiBurro who is a guitar repair genius and an official repair dude for Martin, Taylor and others, turned me on to this stuff after noting that guitar makers like Collings use it). I use the lightest version to clean my motorcycle helmet shield so that stuff is VERY light, and nothing short of amazing. Poly finishes and nitrocellulose finishes differ, but Novus seems to work on anything. Pledge, amazingly, is also useful on lots of woods, and my speakers are covered with vinyl fake wood so anything works...hose 'em off outside, wipe 'em with a sleeping cat, put on a bunny suit and wrestle 'em...