I have been using Hellsman urethane.
I went to a Sherman Willians paint store and they gave me a couple ounces of yellow tint and the same for red.
I care fully mixed them until I got a shade I could live with. I had to stir like crazy because the tint was really sticky and did not dissolve easily in the urethane. Don't add the entire amount of tint but just a little will do.
I applied it to a few pieces of spruce scrap until I was happy. I like using Urethane and when it sets up it continues to turn even more amber and produces a very hard finish.
It's just another way of getting the amber color you like.
The more yellow and red you add the deeper the color gets.
Good Luck,
walter