Assume you are talking about the speakers (versus headphone volume), as you don't specify, but do mention how the sound "travels".
Similar to the above response, I find the volume to be just great. The loudest speakers on any smartphone I've owned, by far. Normally have it at about 2/3 max volume when listening to music with the device somewhat nearby (maybe about 5-10 feet from where I am) and find it plenty loud enough to enjoy and hear details in the sound, etc. But still able to hear people in the room talking to me. The last couple "clicks" on the volume slider are too loud for me under most circumstances, actually. Of course that depends a bit on your own tastes (on how loud you want it), what you are listening to, how far you are from the phone, etc.
Ringtone volume anywhere above maybe 1/3 is obnoxiously loud.
I'd try a different ROM. I'm presently on InsertCoin, which has Harmon Kardon, but does not seem to have affected the overall volume significantly. It might be the ROM you are on, or some result of your settings/configuration. Hopefully its just the ROM, and not some sort of hardware defect.
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Phone: AT&T HTC One (M8)
Tablet: Samsung Galaxy Tab Pro 8.4 (WiFi only)