This is an interesting one. I too have an Octava HDMI switch box and I've been wanting to swap it's SMPS for a linear one for a while but the high current requirement has put me off. I think I have a 1.2A Maplin linear supply somewhere so I guess I could give that a try. My HDMI box isn't a distribution amp, it's just a switch box, so hopefully it won't need the full 2.5A.
Source: Apple TV 4K - DAC: Beresford Bushmaster Mk II - Preamp: CI AudioPLC-1 Mk II - Power Amps: Musical Fidelity 550K mono blocks - Speakers: Wharfedale Opus 3 - Cables: Mark Grant etc - Misc: Belkin PF30 mains filters.