HTC One M9 review: HTC phones it in with a pretty (minor) upgrade Part2

That screen is one we’ve seen before. It’s a 5-inch Super LCD3 display protected by a sheet of Gorilla Glass, with a pixel density of 441ppi. The only thing setting it apart from the panel on the One M8 is a slightly bluer/greener tint and the new single-piece bezel surrounding it; otherwise, it might as well be the same screen. That sounds like a condemnation in a world of super-high-resolution QHD displays, but it’s not: over eight days of testing I never once found myself wishing for more pixels. What I did want was something a little more adaptable in terms of brightness and a little more forgiving in its viewing angles, but overall the display is fine.
The BoomSound speakers flanking that screen have gotten even more capable in the One M9 with the addition of Dolby 5.1 surround sound. The price HTC pays for this sound quality hasn’t changed; the M9 is still taller than many smartphones due to the gap beneath the display, which accommodates hardware displaced by the speakers’ large chamber size. The tradeoff is absolutely worth it, though: against other smartphones with front-firing speakers like the Moto X or Nexus 6, the One M9’s sound isn’t always louder, but it is better. Those improvements carry over to private listening as well, with the increasingly common 24-bit/192 kHz audio support bolstered by a dedicated amplifier whether you use the included earbuds or not.