An XDA developer user has churned out a pre rooted, deodexed and Xposed ROM for the HTC One A9 android phone. It is based on the official firmware from HTC. It is bug free and fine for daily use. In order to flash it, you must be on 1.56 or higher firmware.
Here are its features:
htc car, htc widgets
HTC Boom sound for internal speakers
SenseCamera can read barcodes now
reduced rom size
To flash the ROM, download the firmware from here and put it into HTC One A9 recovery mode. Flash it from there. Again this firmware is based on stock ROM so there are no bugs. Let us know if you have any.