several ways to light a scene with a dome or the background. 1st: if I use a dome I just use the simple Envirosphere single dome prop. It's easy to use and I can make changes quickly. 2nd, if you want more light in your scene using a dome there are a number of ways to do it without having to load up a Poser light and ruin the mood or thrash about trying  to match the ambient lights. 3rd: you absolutely DO get specularity using background lighting.

W10, Ryzen 5 1600x, 16Gb,RTX2060Super+GTX980, PP11, 11.3.740