Primaluna Integrated with a seperate preamp

The updated versions of The Prologue and Dialogue Premium with an HT input has a true pass-through that eliminates the preamp section. Here is the description in the latest owner's manual:

Stereo Home Theater Pass Thru  
The PrimaLuna DiaLogue Premium Integrated Amplifier is equipped with a home theater pass thru that allows you to enjoy your stereo source material and the 2 main channels of your separate home theater processor. This is a true pass-thru circuit. Most integrated amps that advertise having home theater pass thru circuits are only “unity gain” circuits. This means the volume is set at a pre-determined level, but the preamp section is still active and can introduce unwanted noise and coloration to the sound. The home theater pass thru of the DiaLogue Premium HP Integrated Amplifier completely removes the preamp section from the signal path. This is a “direct-line” circuit that results in a lower noise floor, and less coloration.

The only issue I find with the HT input is that it is the only input with tube hum / noise. With or without anything connected to the HT input. All other inputs utilizing the preamp section are dead quiet. I tried grounding and cheating the ground of the amplifier but no effect. Is the tube hum / noise due to the fact that the HT input goes directly to the power section / tubes? 

I’m a believer in separates, and I have a Don Sachs Model 2 Preamp, with a pair of PSVANE Treasure CV181 + a pair of Shuguang CV181 on buffer. But I chose the Primaluna Dialogue Premium Integrated, among other reasons, for having a preamp bypass or HT section, that allows flexibility to be used with or without a separate preamp. Why didn’t I just buy the Dialogue Power Amp? Well experience taught me that Integrateds are a lot easier to sell later on, just in case.
My other amp is a Line Magnetic 518 Integrated Amplifier, a SET amplifier utilizing 845 tubes, which also has a bypass called Pre-In. The 518s preamp section is "so-so" and using it as a power amp takes it to another level. I have purchased about 8 various preamps, from solid state to tube preamps, until I tried Don Sachs’ preamp, that finally ended my search.
Now back to the Dialogue Integrated + a Preamp. The built-in preamp section of the Dialogue is dead quiet as you all know already, and is a decent preamp. But it is not a great preamp section. After almost 40 hours of burning in my Dialogue and using it as an integrated, I decided to finally use the HT input and connect my Don Sachs Model 2 Preamp. The result was a shift from 1st gear to 4th. The soundstage just became wider and deeper, with imaging becoming more holographic. Clarity and details were enhanced. Bass has more weight and finesse, with a layered texture. Decay and nuance in notes is accentuated further with the preamp. Everything just got better by a mile. Now the burning in will continue with my Dialogue Premium Integrated on HT + my Preamp.
I just have to live with the slight hum/noise on the HT input, that might be getting emphasized by the high sensitivity of my Tekton Design Lore speakers at 96db, but its not more than usual for tube power amps.
So yes, the Dialogue Premium Integrated is also a great performing Power Amp when combined with a stellar Preamp.

It’s called Versatility wolf_garcia. Not a lot of amplifiers out there are both an Integrated and a Power Amp. These Primalunas are, and among the few that are highly capable and solid performers.
Equipment breaks down, tubes become noisy and all of sudden die out, and if my separate preamp does that and am out of spares, it will not stop me from playing and enjoying music because I will just connect everything direct to my Dialogue. Flexibility. Options. I’ve been in this hobby long enough to know these are important things. Peace and enjoy your music..