Thanks for the input, keep it coming. Am particularly interested in any comments from those who have had an I5 in the past and moved on to something that they like better.
To address a few of the comments made so far...
At the moment I'm looking mostly at used gear, and as such don't want to borrow any gear from a retailer - if I borrow a piece of gear, it has to at least be under consideration for purchase from that retailer. The way I see it, if I expect my preferred dealers to treat me fairly, I have to do the same to them.
I have done a fair bit of experimenting with cables, power conditioning etc., but the one area where I could look before going "big" is speaker cables - although based on the Kimbers' reputation, what I am hearing doesn't come from them.
I agree that separates doesn't always equal better sound - I previously had a passive preamp and Bryston power amp, and that setup was easily bettered by the I5, and the upgrade didn't wind up costing any money. But, I worry that an AX-7e would be more of a sideways step from an I5 and wouldn't be a worthwhile change, as it would be more of a change (some improvements, some drawbacks) than an upgrade.
In general, if I'm gonna upgrade, I'd like to make sure that it will be a real upgrade, not an incremental upgrade. The I5 really is very good, so that makes it harder to be sure.
The first step would be to buy a power amp and use the pre-outs from the I5, and then step 2 would be to replace the I5 with a preamp...of course, all of this would entail the purchase of 3 balanced interconnects as well, so it's not a minor project!!!