Anyone refinished a plinth?

Piano black with no grain showing will require many coats of sandable primer. You can use spray cans but pro automotive primer will be better. Slightly ease all sharp edges before applying primer. Build up the primer sanding between coats with 200 grit wet or dry paper using a flat sanding block. Always keep the sanding block flat. Stay off the edges. Once sealed wet sanding can be done.
Once you have the primer built up so no grain is showing, I would give it another coat and sand with 400 grit paper.
Then you are ready for the black lacquer. I use automotive paint which will look the best and be very hard. Real lacquer has been outlawed by the EPA so it will probably be acrylic lacquer. You can probably do the job with Rustoleum Hardhat spray and have a decent looking finish but pro automotive paint would be better.
If using pro paint, you must mix with thinner and maybe a catalyst to harden the finish. You will need a good sprayer and compressor with a moisture collector or an airless sprayer(preferable) Wipe down the table with a tack rag and apply three coats of finish about fifteen minutes apart. Let harden overnight.
The finish will probably have a slight orange peel and not be very glossy. Using 400 wet or dry paper sand till nearly smooth. Be very careful on the edges, just sand slightly. Using water while sanding makes it easier just be careful not to get it where it shouldn't be. Then go to 600, 800, 1000, 1200 and 1500 grit. After that it needs to be buffed with swirl mark remover. You can also apply a clear coat if wanted.
It's really pretty simple.

you can also get some paper-backed veneer (parts express sells it), cut it to size and press it on--if your woodworking skills match mine, it'll save you some heartache. i've recovered speakers with it and it can look really good.

Concidering the time , effort and cost of what your trying to attempt to do as you are an admitted novice and the risk of a less than happy outcome...... You would be very surprised at the lower price than you think it would be for a new plinth to be made. Few on here that advertise so why not at least check that option and make your decision.

As noted sanding veneer is risky and to get the effect you want the finish on it now will have to be removed from the grain for it to show with definition as you are wanting through the black. Stripping veneer is also a risk if the chemicals are to harsh or the veneer so thin that it effects the glue and can cause it to ripple and so can applying a top coat to heavily when finishing it.

If your adament about doing it and with 40 years of woodworking and refinishing I am confident for you to get the results you wish for.
1. Do not use any sandpaper no matter how fine.
2. Use a waterbased stripper and medium steelwool to "lightly" remove the bulk of the finish being carfull not to use to much to soak the veneer.
3. Do not use any! scrapers of any sort only the steel wool.
4. Use some cheese cloth to wipe away the dissolved excesse finish. Can be bought cheap at home depot and works best because the open weave traps the dissolved finish where a rag will push it back in to the grain.
5. Use a fine steel wool with stripper to remove the remainder of finish using the same methods and cautions above.
6. Let it sit and dry naturally for a day then use XXX fine stell wool to "lightly" remove any stripper and dirt that comes up from the surface leaving a nice smooth clean surface and finish with clean tack cloths turning them frequently.
7. Use a flat black dye/stain with a cheese cloth. Put the stain on the cloth not on the veneer. Work it in with the grain and Do Not use to much to soak it. 2 or 3 light coats never one heavy one. After each light application and some drying time use a clean peice of cheesecloth to wipe and polish the stain evening out any irregularities.
8. After leaving the stain to completely dry and you can wipe a piece of cheese cloth on it and pick up no stain.Apply a seal to it with a compatible product with the stain you used.(min wax for both is a safe bet but read the labels as they are not all compatable with each other) I would recommend a wipe on finish for two reasons. It provides a more uniform finish and no risk of over soaking the old veneer . Lightly wipe on using cheese cloth. Let it dry and very lightly polish with XXX fine steel wool. this is only to allow the next coat to adhere so very lightly.Tack rag then apply final coat.
I would recommend a flat satin finish as the previous finish in the grain will let the grain have more definition and show more naturally.

Good Luck and remember if you rush the process it will show in the results.

Cheers.

I have been doing repairs and finishes on stringed instruments for years and, for the effect you're trying to achieve, 4est has the right idea. The term for a transparent coat with color (dye) is a "toner". Behlens makes a wide range of toners in spray cans.

The way to proceed would depend a lot on the existing finish. I think some of the Thorens tables may have been oiled walnut. One potential problem no one has mentioned is the possibility that someone has used a furniture polish containing silicone. It's definitely a game-changer! Assuming no silicone, it's possible that you could wipe the plinth down with naptha (lighter fluid) and spray light coats of toner until it's the desired shade, followed by a couple of clear coats. Personally, I would seal it with a couple light coats of a 1 lb. cut of shellac before the toner, but it's not an off-the-shelf product. Depending on the look you're after, you could actually be done at this point. If you want a mirror finish, you got some work to do.

I use strictly nitrocellulose lacquer which, contrary to popular belief, has NOT been banned. Google "guitar refinishing" and you will find endless sources for this wonderful finish.

For a nitro piano black, you should start with a nice flat surface. Rwwear has the right idea for the primer, but once it has been sanded flat, I would proceed differently for nitro. Once you have a good coat of black, you can lightly dry sand to knock off the dust and minor imperfections. Pigmented nitro is not very durable, so you follow that with numerous coats of clear nitro. Then, I highly recommend you let the nitro harden for several weeks before proceeding. Then follow Rwwear's wet-sanding and buffing instructions, but DO NOT follow with another clear coat.

I guess outlawed is too strong a word. But nitrocellulose is difficult to find at automotive paint stores. I have gotten it from Stewmac.