Streamer ugrade options please

Hi Thanks for reading.

I have a dune d1 streamer which i am using for playback of music and movies from a usb 3.0 hard drive.
The dune has hdmi out which i am connecting to a screen for the picture, and the dune has analogue stereo output which i am connecting to a power amp for the sound.
The sound and picture is good but i am wanting to upgrade to an audiophile set up with 5.1, so am thinking of purchasing a high-end blu ray player which has 5.1 analogue outputs, also hdmi out for the picture.
Can you recommend such a blu ray player. I need one with a volume control as the power amp i am using does not have that, and upmixing / downmixing functions, audio eq etc. The blu ray player must be able to decode dts ha ma and dolby true hd
I would like to purchase an older model as brand new releases tend to be expensive, the price drops rapidly when manufacturers release a new model and they discount older models to get rid of them.
Alternatively, a 5.1 streamer would do the job fine. I have looked around but cannot find one. Can you recommed.

Many thanks.