Have not tried any DHT pre yet. Latest addition I made to setup is a 3KVA Online Ups from APC. Finally got my peace of mind. Also realising XLR to RCA conversion is introducing some hum. The speakers are dead silent when I connect via balanced XLR IN/OUT but not when I am using the conversion. Have used multiple cables till hum persists. So hunt for a pre comes with mandatory ask of balanced XLR inputs and outputs.
The choice of a tube pre with balanced out is a smaller group to choose from ! I would suspect that in your setup ,becuse of the gain, you just might get that little more transparency from a Passive pre..advantage is while the system gain is lower, higher transparency and lower noise.
For Passive- Music First. I believe the Schiit Freya also has a passive mode
Active- Modwright , Audio research, Silvercore...and so many more.