I am an Electrical and Electronics Engineer and frankly think that the comment made to you about direct power connection is a fallacy. My house has a ring-main power distribution system and here in the UK our line voltage and frequency are one of the most stable in the world.
My online discussion with Epson Support on this matter was not satisfactory. He did not answer my question as to whether he was an expert regarding this model. He also said early in the discussion that I should return the printer to the supplier.
Later after much pressing on my part he said that the printer does not do any housekeeping purging unless manually initiated.
Just five minutes ago from standby I printed four A4 text sheets. Before printing the R3000 decided to purge all lines and I sat and watched it doing this three minute process.
I want to escalate this problem but Epson support offers no option to do this.
All the marketing hype in the world does not make up for poor service.
Maybe some one at Epson is on Nikonians and will realise just how many thousands of potential buyers reading my post might be put off buying this otherwise great product.