My opinion is that for a 1.78 screen, you do not want to be any closer than 1.3 to 1.5 times the screen width back. This is a good rule of thumb.

M80s VP180 4xM22ow 4xM3ic EP600 2xEP350
AnthemAVM60 Outlaw7700 EmoA500 Epson5040UB FluanceRT85