[HeadphoneAddict]

The RSA P-51 has been a good match for the UM3X and gives them a bigger soundstage than the Predator or the stock D10 which sounds like a Predator with the stock opamps. The D10 with TLE2141 class A opamps and EL8201 as buffers opens up and gets much closer to the P-51 with just a little less air and spaciousness in the top end vs the P-51.

Those are the only two amps I have tried with the UM3X (P-51 at a couple of meets, and D10 stock at July CO meet, and D10 with the above opamps at RMAF).

 

[VicAjax]

early impressions seem to point to the ALO Rx amp playing nicely with the UM3X as well. it's on my shortlist.