Igros Moshe(Y.D. 1:223): You bring from Sefer HaIkkarim (4:15) that the reason that Moshe did not break the Tablets immediately when G‑d told him that the Jews had made the Golden Calf was because seeing is more powerfully real than knowledge. In my humble opinion, G‑d forbid to say that when Moshe heard about the Golden Calf that it was less significant to him than when he saw it himself - even in terms of emotional response. A possible explanation of why he broke the Tablets only after seeing the Golden Calf, because G‑d did not tell him about their enthusiastic dancing and therefore he thought it would be enough if they saw him - to completely repent immediately. However when he saw their enthusiastic dancing he realized that they would not so readily repent and therefore he broke the Tablets. You can also say that that he waited to break them so that the Jewish people could see him break the Tablets and realize the great loss they had caused because of the sin of the Golden Calf. This is stated explicitly in Devorim (9:14), “I broke the Tablets before their eyes.” This implies that he deliberately did it before their eyes. In addition it says later more explicitly in Devarim (34:12), “Before the eyes of all Israel.” Rashi explains this verse to mean that he intended to break the Tablets before their eyes. If so he had don possibility of breaking it when he first heard from G‑d about the Calf before he descended from the mountain. He was thus forced to wait until he descended so they could all see that he was breaking the Tablets. In contrast regarding hearing something from another person it is definitely true that seeing is more powerful in eliciting emotions and there is no need to bring a proof to something so obvious.
Igros Moshe(O.C. 3:50): I replied to you many years ago and my reply was printed in my Igros Moshe (1:223) that G‑d forbid to say about Moshe that what he saw with his own eyes was much more real than what he heard from G‑d and that is the reason that he only broke the Tablets after he saw the Golden Calf with his own eyes. Now you write to me that the Akeidas Yitzchok also shares the view of the Sefer HaIkkarim. I in fact looked into the Sefer HaIkkarim and I saw that in fact he agrees with my view that there is no difference between hearing information from G‑d to seeing it oneself. He brings a medrash that the reason that Moshe didn’t break the Tablets previously was in order to inform the Jews that it is prohibited to act on knowledge – even absolutely certain knowledge until it is directly witnessed… The Akeidas Yitzchok himself wanted to say that Moshe wanted to break the Tablets in front of the Jews in order to magnify the message to increase their discomfort at sinning. This is a strong reason and I my explanation anticipates this as I wrote previously.
In contrast in Darash Moshe (Yisro):