After talking to David Beetles (Hammertone Audio) about the upgrade available for the H3000, I had Albert Porter (PorterHouse Audio) up grade my H3000. David described the improvements as "greater dynamics, wider bandwith and soundstaging abilities", Albert's description was similar. My reaction to my upgraded unit is WOW. The upgrade raises the H3000 to a new level.
I would add that I us a Mullard GZ37 brown base rectifier tube.
I would add that I us a Mullard GZ37 brown base rectifier tube.