I have a preferences for round core strings, TI rounds, DR Sunbeams & Hibeams. I've noticed that round core strings have certain advantages, & of course, with something gained there is something lost. Hex cores do give you a very hard "punch in the gut" transient. Round cores sustain more, particularly Sunbeams. I'm told those hex cores are stiffer & have more mass. This is probably a stupid question to which there's an obvious answer but: How can hex cores have more more mass than rounds? If there are wrapped outer layers, then shouldn't the wrap around round cores be tighter, denser. Conversely, wrapping around a hex core would have eight small gaps filled with air. Duh? Also, I know that TIs have a buffer layer of silk & are an exception. Remarkable, considering their flexibility, they do have a surprisingly hard transient pop to them.