Just realised I hadn't replied.
Set-up : X7 original to Q5 via coax. Files have been a mixture of redbook, 24/96, and some aac256. So far 7 hours in - and no signs of it quitting yet. If you are only getting 5 hours - I'd get your battery checked. IMO - something is wrong.
Thank you Brooko.
You didn’t mention the headphones you used for the test, and the volume level you have set.
It should probably last longer without headphones, as line output only...