The bass wasn't a problem on the one I heard - literally, the treble was refined because there was none.  It was really really muted - like I say, like listening to a tape deck with slightly dirty heads - the top end was muffled.  Veiled - what have you.

The CD5 in comparision was much better.

To be fair though - as mentioned, the 5i might not have had many hours on it, and I'm hopefully going to find out today what a NON-run in CD5 sounds like - provided Naim's delivered one to Audo-eXcellence today (they "forgot" to include the 2 AX had ordered on Wednesday - grrrrrrrrrr).