q10 pro will do nicely for you; it is an excellent player for local media playback, various video settings with imprex 2.0 engine, auto frame switching.

it has hdmi for tv... 4ktv... u will love the picture quality if you play big good files.

and u also get tv audio with hdmi.

it has coaxial and toslink for digital (dd/dts) output, can use either for yr old amp/avr.

if the file has dtshdma/ddtruehd/ddatmos/dtsx, the player will find the right audio or downgrade to core dd/dts for yr amp/avr.

on top of what nicety has explained...

.. it will take u time to learn, understand and get the max out of an android box which is not at all same as astro or hypptv boxes.
.. android boxes come in all shapes n sizes, some are cheap but poor in performance; some are pricier but capable of many things.
.. q10pro is among the best u can find now; q5pro is a small brother version - basically less storage memory, and w/o an internal HDD slot.
.. there are free apps, there are paid apps; there are reliable apps, there are unreliable apps.
.. if u know enough and find hard enough, there are some fairly reliable free apps/channels but will not be 100%.
.. the key to free apps is to have constant new app updates, and several in use so that there is enough to watch at any time.
.. nicety has a place for u to get them, so that is a great plus!

u started by saying u want to playback with HDD. for that, q5/q10pro will serve u well as the video n audio quality delivered is excellent, assuming u play good files.

i use q10pro a lot for playback of bluray, 4k, hd audio files with home theater, very good.

note: i m user, nicety is seller. i have been user of himedia boxes for 5 years now.