r/vintagetech

So my dad has kept this for however many years, its never been used, still in original packaging, papers and box. Aswell as all the wires and spare fuses.

How much could this possibly be worth? (Rough ballpark) and where could i possibly sell it? Are there any selling websites for old vintage technology? Some help would be much appreciated.

It’s like a soundboard (not what it is I know) but I just don’t seem to have the cable that connects it to my computer. If anybody knows the type of cable that has an HDMI and a side that can go into here that would be appreciated! Thanks!