Thanks for your extended comments, Wisnon!
Regarding tubes, I have run my balanced GG1 (with R2R PCM upgrade) actually in SE mode with the Psvane WE 101D Replica tubes, preferring this against 6A3's, Psvane 300B's, Takatsuki 300B's, RCA 45's.....and others I cannot recall. But a couple of months ago I purchase some Kron KR T-100 output tubes, and these I like the best, by far - - more detailed extension and a dynamically livelier presentation, while also have very good harmonic bloom. I also use the regular KR 5U4G rectifier, which makes the 101D's or the T-100's both sing better. These tube adjustments have made a very noticeable upgrade to my GG1 sound.
I listened to a Pacific at an owner's house on a stereo that was all new to me, and in an incredible room that was all new to me, and I liked what I heard, very much. But was it the stereo + room? Are the speakers voiced to match the Pacific better, and my speakers voiced to match the GG better? These are my fearful questions. Your reply is helping to calm my fears a bit. The GG1 I have just sounds like musicians in the studio making great recordings, and it does have a bit of the "warts and all" revelation of information that gives a bad mastering no place to hide. I just don't want to go too far over on that side. Sigh....
I brought a bunch of tubes to roll in the Pacific for my visit, with the clear winner being the supplied Kron KR 300B's that come with the DAC. We both heard it as best. To my ear the T-100 was a little too vibrant than real life, the KR 300B's offering a sound that just felt like uneditorialized life, fully revealed with all of the musical information that the Pacific taps. My host liked the Takatsuki 300B's enough that he chased down a pair to add to his options, but the T-100's did not move him in like manner (and the Psvane WE 101D replicas were not in the same league, in this DAC).
In the end, I have a Pacific upgrade on order, due to arrive in early November, so I will find out then!