How to elevate a solid state tube heater supply?
In your question, you are attempting to connect the "heater" to the B+ tube power supply.  

The B+ in your system is essentially connected to the Anode (Plate) of the tube (P,  pin 5 in symbol below).  



The heater in a vacuum tube is more closely associated with the Cathode ( K in the tube symbol above). The first vacuum tubes used a directly heated cathode before filaments (heaters) were created.
   Filament heaters INDIRECTLY heat the cathode (electrically isolated).  

In most common vacuum tube circuits, the cathode is more closely related to ground (common of power supply), much as the emitter of a NPN transistor in a common emitter configuration.   

Vacuum tube data sheets can show "Maximum Ratings" such as (12AU6) : 



Notice that there is a maximum 180 voltage rating (12AU6) for "cathode to heater".   I did not find a maximum in the specifications for the tubes you have selected. But beware anyway. 

I have not seen any circuits where filaments (heaters) have been referenced to the B+ power supply.   

For further information on audio and filaments (heaters), Here is a good page to start with  .  

EDIT :  ECC81 is same as 12AT7  :  Maximum 90 volts Heater to Cathode.