[OldRestorer]

No, If the radio is one shade now, adding toner will not change it. It will make everything darker and stay uniform unless you already have contrasting colors on the radio. You can tone the cabinet perfect brown first and then see. I would not use medium walnut since it is very similar to perfect brown. Maybe use light walnut then medium walnut.

As for the second half, Please know that wood filler and grain filler are totally different. You would use grain filler since walnut is porous and it will fill the grains and make for a glass like finish. Not a necessity but it definitely helps the look and keep it true to its original look. Sealer is not something I use much, the clear lacquer and toners are going to seal the wood.

Kirk