Sorry, tube power amps do much more than the linear portions of freq response which is the only aspect that standard IR's like OH's can do.
Tube preamps NEED tube power amp sim (as well as cab sims if DI'd etc), to sound their best ASSUMING one wants to sound like a full tube amp rather than a stand alone preamp etc.
I've been able to get my tube pre's sounding good with the Ultra's Tube-Pre, instructions below...
EDIT: I've found a way to use the Ultra's Tube-Pre for a pseudo tube power amp sim with my tube preamps which now sounds as good as the Torpedo's, and here are the details...
a) I set my tube preamp's tone stack as flat as possible (typically bass and mid up, treble down, but it varies). The Seymour Duncan Tone Stack Calc for Windows works well for this!
b) I then instantiate a amp block with the Tube-Pre, and then pick a tone-stack for my rather flat sounding tube pre. I set the Tube-Pre's gain to zero, Master Volume to ten.
c) I then turn on the Tube-Pre's power section by turning Sag up from zero, and while leaving the Tube-Pre's tone stack flat, adjust the various power amp parameters to what I need considering the gain structure and tone of the tube preamp, and the selected tone stack in the Tube-Pre (I'll look at the modeled amp's power amp settings for ideas and tweak from there etc).
Leave the Tube-Pre's gain at zero and make up gain elsewhere as needed (Level, FX Loop etc, you;ll need quite a bit).
I've tried it with relatively clean through edge-of-breakup Fender/Vox, to pushed mid-gain modded Marshall/Mesa type tones with good success.
It doesn't really bloom as good as the Torpedo's tube power amp sims, but aside from that easily as good seeing that this is all subjective in nature.
The OP doesn't need to use the amp block at all or buy some Two Notes product.
Just place a PEQ block after the Cab block. Set it for a bell curve set to -3 dB at 400 Hz. Adjust the Q/bandwidth to roughly where the edges of the curve start to make the initial cut around 100 Hz on the low side and 2 kHz on the high side.
This is what OwnHammer recommends doing to their IR's if you want to replicate the sound of IR’s that were instead driven by a guitar tube power amp with the Presence and Depth set to 0, which results in a mid scoop.