FWIW, I have committed to the 5900 (instead of 2900 or Sony), and I have one on its way to ModWright for the Signature Truth Tube, MCH, Bybee, and perhaps some other mods. I'll be sure to share my results when it arrives, but as I am having it sent directly to Dan, I will not have an opportunity to compare stock to modded.
Tom.
Tom.