Okay guys, three units are in the works right now...
The 5900 Tube mods will feature the following:
1) Outboard high-voltage supply with choke input and FET regulation.
2) 6H30 based Class A tube stage - more advanced that circuit in 2900 mods.
3) Passive and active cooling techniques as tubes are internal. I.e. chassis is machined and a small fan is being investigated for add'l cooling.
4) Op-amp free analog stage (2CH only) with passive I-V conversion.
5) ZERO feedback design for 2CH.
Price: $1600.
More information will be posted on the website soon.
Thanks,
Dan