There is such a lot of different components changed in one shot it would be difficult to say what caused the improvements.Tube type,Audio note resistors,Internal Wire type,Transformers,Cardas parafeed caps versus Kimber,Direct to power amp connection. I thought in my system my homemade unit had a reasonable margin over the Pass X ono and most although not all friends agreed, it was no contest when the new unit was compared to my dual mono and I tried lots of load settings and cable changes etc before selling the unit.