Hi guys,
Thanks for noticing. This kit came together in about ten days and as usual it will have some upgrades available as we develop them. Yes, it is designed for high impedance headphones. Most of the phones that I happen to like these days are high impedance and I feel that this type of design works especially well with them. Since we already make another headphone amp that can easily drive low impedance headphones I figured we could put one out that is a little more defined in purpose. Yes, I suppose the design is similar to the Van Waarde design - which is of course similar to the Dubiel Acoustics HV-1 - which is of course similar to the Pete Millet Wheatfield HA-2 - Woo Audio 2 - etc., etc. etc. including every amp that ever used a 6AS7/6080. After 16 years in the tube audio business I can guarantee that you can find a precedent for every circuit concept, things just get rearranged into a newer execution of an idea.
IMO AC heating is perfectly reasonable in this relatively low gain IDHT circuit Note that we use a 12AU7 which has quite a bit less gain than a 6922. It's a very quiet amp. Hopefully the price will be an attractive feature for those who don't mind doing a little construction.
