Morgan,

Also, where are you treble and bass knobs, and the bias and impedance switches.

Hey Morgan, Those answers will help. By the way, your impedance switch is toward the higher value (back) and the bias is on the higher value too (front). Together you are set on fully cranked.

And I guess you have explored lower bass knob setting to open up the low mid/bass a bit??? That would chill the dark aspect of warmth anyway. They are odd compared to the usual. To me, the bass knob right gives fuller/rounder bass, but also some nice textures. And left, tighter, more open bass/low mids, but a little tighter sound throughout. That balance is always changing a bit on my amp when I switch tubes. I don't know about you, but I find that bass knobs do quite a lot when you listen to the full spectrum of the music, and 1/8 turn can be important.

If you look at my post before last I had some thoughts as to how to head somewhere based on what tubes you are using, and asking specifically what you would like to be different. I have messed with a lot of tubes and might be able to give some simple suggestions toward your goal if I had a clearer idea of it. Maybe anyway.

Morgan, I think those two inputs will be a nice test sets for you. I look forward to your impressions. Yes.....the breaking in thing along with moderate volumes, I get your reticence to evaluate. Especially for the speakers, but those Nationals will take a while to settle down and smooth in, and Lon says likewise for the 6N1P.

What I meant by cranked from the switches: the higher impedance sounds to me like it pushes the speakers harder and also faster???. A bit louder, a bit more present with an increased articulation that seems to come from more push/punch rather than more detail. I don't think of this as good or bad, but is a great tool for tuning to different speakers of other system factors as you have found. I tend to always be impressed with mine at the back/high setting, but fall back to the front/low setting preferring the more open relaxed sound. But that is my system/room and taste, and I don't think there is a "right" setting for this.

I think the bias switch in the forward position actually pushes up the bias of the output tubes a bit. The back position is more neutral. So forward, I think we get more presence and warmth, with a bit more across the spectrum .... a touch more upper mid emphasis, fuller mid-mids, more bass punch.....

So with both in the high positions, the amp is set to its higher output settings so to speak. This is what I meant by the amp being fully cranked...yours is set for exactly what you hear, with more presence and power which manifests as more warmth and intimacy in your setting.

I play around with my bass and treble knobs a lot. With tube changes, as little as a 1/8 turn here or there is important to me now that I understand them. One thing I find really cool about them both is how you can tune the sound stage with them nudging the center vocal exactly into the center with fine tuning. Or if all is well with the sound stage center, but one side of the room seems a little less sparkly...just a little tweak the knobs, very slightly tightening the bass (bass left), or punching the highs (treble right), or both, can bring everything into the beauty.

I tend to run mine with both the bass and treble knobs in the 11-1 o'clock range providing the sweet area for me in this system/room. But I don't think there is a right setting. They are there to help get you where you feel the best about the music.

I think the trickiest thing to figure out for me was the bass knobs. I find that they tighten or relax the sound throughout the spectrum, though it is most apparent with the bass. So I am always looking for that place where the bass only just tight enough because I love the midrange texture that comes with this setting, tight enough, but still warmish.

Morgan, amazing amps aren't they? So glad you've been enjoying yours so deeply. Nice too that you are close enough to Michael to have an audio buddy that way!