@gakerty , there’s a fairly long thread on audiocircle in the discless circle focusing on the mp-d2. The sound is fairly easy to tailor through tube, cap, and chip swaps. Also, your 12au7s could be put to use here. There’s an internal switch that allows for 12.6v filament signal tubes.
My version had the AKM4497 chip, Silver/Gold oil M caps, a pair of NOS Amperex tubes and a number of vintage 5U4G rectifiers.
I feel this DAC is one of the best bargains on the market, especially on the used market. It runs dead quiet, has fantastic sound, and is easy to integrate into systems without having to go through whole component swaps. Signal tubes and rectifier tube swaps offer a lot of flexibility. I would have been very happy to keep the MP but was tempted by all the Holo May dac talk and caved. I needed to sell the MP-D2 to help fund the purchase. I have no reservations recommending the MP-D2 to anyone in this price point, and I feel the MK2 models offer the best bang for the buck.