Rogue audio RP-7 versus PS Audio BHK preamplifier

All you have to do to change the tonal balance of the BHK is change a pair of tubes.  It can use 6,7 and 12 volt tubes with a change of the jumper.  Not the case with the Rogue which takes twice as many tubes and only one type.  

The obvious choice is usually Mullard but they are getting very expensive if you buy from a reputable seller like Andy at VTS.  A more cost effective alternative are the tubes made in the Matsushita factory in Japan that was set up with the help of Mullard and used many of their tooling and methods.  They were available with under many labels other than their own.  Last I checked Andy had a good supply.  I also have had good luck with the Black Plate Raytheons and Toshiba's that were available as tubes from the organ companies like Conn and Baldwin.  I was not as impressed with the 6 and 7 volt tubes and I tried quite a few.  The best were the Matsushita's and the Phillip's that Kevin was selling.  Both are on the warmer side.  One thing to consider with the BHK is that it greatly prefers tubes that are not only matched to each other but also have matched Triodes.  The best of the current production tubes is probably the Gold Lion which you can buy that way from the TubeStore for under $100 a pair.  You probably can't go wrong with either choice but I have never owned a Rogue preamp only amps.  Another good possibility is the Backert Rhuma 1.3.