For HDMI, I have used simple powered HDMI splitters(around $36) and run 50' HDMI cables with no issues(at 1080P). Never tired this with a 4K signal. As for USB, I have used 50' powered USB extension cables(they have a lump near one end that amplifies the signal) and they work fine(used one for a remote keyboard/trackpad and another to use an Akai trigger unit for midi signals). No problems in either case
