I can hear the hiss loudly enough to annoy me when playing the EVs at normal playing levels, either through Sennheiser HD25 headphones, JBL EON 15G2s, Behringer B210ds (don't laugh), or the Mordaunt-Short system that I use with my disklavier. It is far worse when playing quiet passages, and with large chords, but it is still there all the time, and it is clearly evident in the recording I made (which was straight out of the SK1 into a Zoom H4n). I think this rules out something in the external signal chain or impedance matching issues.
I will be contacting Hammond when I return home in a week or so about this issue. I regret buying from a small independent (but fairly local) store; if I had bought from a large chain I would not hesitate in returning it and get a Nord (or possibly a Kronos, but I don't see any deals anything like as good in the UK as the one mentioned here!).
Another sticking point: there is also clicking in some of the loops, eg Rhodes 1 near the bottom of the 61 key keyboard has samples that click, and there are higher up notes that have tremolo effects because of bad loops.
Then there is the trigger point on the organ. Yes, you get used to it - kind of - but it still trips you up, and it is *really* annoying from a keyboard sold as an Electro competitor. It makes squabbling, smooth slurred runs, palm taps, alsorts of things harder than they need to be.