Isaac has a nice Sony home theater system. But with 4K, he wants to know if the difference in quality is worth rebuilding it in 4K. Leo says that Blu-ray is not only 4 times the resolution as 1080p, it also has the high dynamic range and that's more important. If his home theater supports HDR, then there's no problem. If not, he may want to think about it. Moving forward, he can start picking up UHD HDR Blu-rays for his collection. Billy Lynn, Master and Commander, the BBC Earth series — all are excellent.