Is it possible to still mine LTC or EHR on a PC or are those days long gone too?
What about say 5x Antminer S9...worth it for BTC or waste of time?
It's possible but would take a very, very long time to mine anything of substance. You'd make more money faster using faucets!
A mining machine will mine coins faster but you have to take into account how much the electricity will cost (and the cost of the machine). In most cases, in the central latitudes of the world, electricity is too expensive to allow the return you would get from one machine to earn you a net profit. What you'd earn in bitcoin you'd be spending in electricity to produce that Bitcoin.
There are sites that will do the cost benefit analysis for you if you enter in details about your hardware and electricity costs.
Honestly, the fastest way to earn bitcoin is to just do work for wages and use those wages to buy bitcoin.
