speaker wood care

wood likes to be dry. It's moisture that causes a problem. You will get lots of recommendations, mostly from people who are not wood workers.

I wouldn't apply anything.

S7horton is both right and wrong. First and foremost avoid large changes in ambient humidity. Too wet is usually the case, but too dry can be just as bad. When the moisture content falls below 6-7% the cellulose bonds within the wood become very brittle and can crack (could affect the sound in something that relies on box reverberation). As for applying something, a lot depends upon the finish type and none of them will add moisture nor will anything keep the speakers from losing moisture in order to reach stasis with the environment. With that said, it is hard to go wrong with a good paste wax such as Johnson's (not auto wax) to protect the finish. Ultimately, you should consider adding moisture if it is really that dry. FWIW, an air washer (filter) such as a Venta should work great for you.

Disclaimer: I am a cabinet maker

Lemon oil works for me,S7horton has 1/2 of it right also.Extreme dryness will cause cracks depending on many variables,thickness,type,temps,changes,finish etc. etc......common MDF with a veneer[common in speakers]could use a little TLC.1.5" solid wood[unusual for speakers]won't be cracking much if at all,figure what you have,google wood finishes,then go to the yellow pages under furniture,make some calls,listen and learn,then go and score 1 or 2 products and try out.Wood is so interesting you can't go wrong investing a couple of hours and 15-20$.Need to know what you have first,good luck,now get to work....