I'm about to become a TiVo orphan and divided between replacing it with a homemade HTPC (on a modest budget) or a set top box offering from Panasonic.  I'm swinging toward a HTPC with MythTV however I can't find anything concrete in terms of minimum/recommended hardware spec or even which software solution to use.

My requirements are:

- a single box that houses both front and backends as the fibre and main terrestrial aerial cable terminate behind the main TV so would like to reduce the number of devices.  We do have a second TV and other devices to stream to but have a Raspberry Pi for an additional frontend

- ideally runs silent/energy efficient

- must output at least 5.1 audio via the HDMI cable

- dual HD terrestrial tuners (such as Hauppauge WinTV-dual HD - https://www.trademe.co.nz/computers/components/other/auction-1418553460.htm)

- a physical remote rather than a software/phone based app

- OnDemand apps (TVNZ, Three, Maori and any others available), Netflix and the other VoD services would be a plus for future proofing.

Not hugely fussed on automatic advert removal and have no need for 4K however these each seem to drive up the specs.

I don't have any suitable hardware laying around other than a 2009 Mac Mini which is probably underpowered for multiple HD inputs given its age.  Would also require a separate frontend as the hardware itself doesn't have HDMI and read somewhere that model of Mini doesn't support multi-channel audio.  Appears everyone's going with the Intel NUC's which support 7.1 audio via HDMI.

Really appreciate some guidance of hardware specs, CPU, RAM etc... if possible as well as a recommended tuner?

Would an entry level 2.0 - 2.3GHz dual or quad core NUC get the job done with ~4GB RAM?

Thanks.