It is fairly common to see US carriers release a customized version of a smartphone, but what Sprint has done is taking things to the next level. The HTC One (M8) offered by Sprint may sport a custom set of Harman/Kardon speakers, with its own enhancement software installed in addition to BoomSound.
First pointed out by @evleaks on Twitter, this thread on XDA Developer’s forum revealed that the model on Sprint, which went on sale by the carrier yesterday, contained an additional “harman/kardon audio” setting in the Settings menu. The system configuration also contains the string “support_harman”, which is on by default on the Sprint model but is off on others.
However, it is not yet confirmed whether this model actually contains a custom harman/kardon speakers, with everyone in the forum thread unable to confirm whether the branding extends beyond software enhancements. Attempts to change the “support_harman” string from “false” to “true” in the system configuration file also proved fruitless, as it automatically reverts to the default setting.
On the other hand, Sprint has previously been known to work closely with HTC in the past, with its range of customized set of EVO smartphones. Then again, having a set of speakers that are arguably better and only limiting it to a small set of its customers does sound highly counter-intuitive. We’ll wait for any official statement from HTC, and update the post when there is one.