Regiggey,
That looks very interesting to me and sounds like it may be precisely what I am looking for. The only problem is my Firstwatt was build from Mr. Pass' DIY plans by Mr. Rawson. I am not technically skilled to perform the upgrades myself, Mr. Rawson has retired and I doubt Mr. Pass would care to work on something he did not build himself...
Audiofeil,
I weigh your feedback very heavily as I realize you have quite a bit more exposure than most to Zu's speakers, but I am very surprised you feel the F1 lacks drive.
Though I have no basis for comparison, I feel as if the F1 really takes control of the driver. Based upon your experience with the F1 and Zu speakers, I am curious as to what you feel is missing.
To my ears the amp doesn't sound soft at all offering very strong bass performance and a clean uncongested mir-range. Its very dynamic and keeps great PRaT.
I'm very curious as to what more power would bring because to my, admittedly less experienced ears, this amp sounds darn powerful.
I'd love to try the higher end First Watt but its a bit out of my budget at the moment... Perhaps you have an outstanding lower cost recommendation? Phil made a compelling case for el34/el84 amps.