I noticed that the reviewer experimented with substituting 12AU7 input/driver tubes. However, the online owner's manual only references substituting 12AT7 (ECC81) tubes. Could this be the source of the softening in the focus that the reviewer noted?
Also, in most circuits, a 5751 can be substituted for a 12AX7 and I am wondering if that is also OK for the i84?
Unfortunately, I haven't had a chance to listen to the i84 but the buzz here on Audio Circle and elsewhere has me very tempted. I have at least 8 vintage EL84 amps and couple of modern ones. I probably need to get rid of a few before a buy a new one.
I am currently using Ed's horns and, based on the Positive Feedback review, the i84 might be a pretty good match. I would be interested in hearing from anyone who has tried this combination.
I also have a pair of LS3/5As, which are very inefficient (83.5dB) but an easy 11 ohm load for most tube amps. I have driven them successfully with other PP EL84 amps (moderate volumes, smallish room) and the i84 might be a great switch hitter for both sets of speakers. aa
In any event, congratulations on the review.