I did this with a set of Aeon Maple rails. They are now Walnut and now match my Salamander walnut AV credenza. My walnut stained maple rails look better with my walnt furniture than natural maple rails.
However, I'm not sure if it was worth it though since it is rather time consuming. You can restain them and they can look good but I don't think they are as nice as natural wood with a clear coat. Here is the process I used.
1. The maple rails have no stain they are just clear coated with polyurethane. You first need to remove the clear coat by sanding it all off. I used a handheld power sander with 40 or 60 grit to get most of it. Sand only enough to remove most of the clear coat with this setup. Don't get too aggressive with it. You don't need to sand the back side since you won't see that anyway when it's on the speaker. But that is up to you. I did.
The advantage to working on the backside is that you can test the stain on that side before working on the viewable side.
2. Hand sand the rest with 100 grit and then 200-400 grit or what it takes to get a smooth finish.
3. You should use a stain prep before staining. It'll help the stain soak into the wood. Use all oil based and not water based stain and clear coat. It just works better in my opinion. Also, stay with the same brand for both. Follow the products instructions.
4. You can now stain the wood and it may take a few coats to get the shade you want. Let it soak in between coats.
5. Once you are satisfied with the stain you are now ready to clear coat. You can sand with fine grit in between coats resmooth the wood but you also have to clean the wood with a damp sponge after sanding. And be sure to let the wood dry before applying another coat. This sanding step is optional.
6. Apply thin coats of clear coat. Don't over apply or you'll have runs and then you will need to sand them out and reapply.
7. Or just buy a real nice natural set in the wood you prefer. Get them at clearance prices while they last.
http://shop.martinlogan.com/merchant.mvc?Screen=CTGY&Store_Code=xtatic&Category_Code=rail_clearance