I don't really own many amps, so I can not confirm if the MJ2 lack sub-bass. I am currently using the mj2 / gungnir MB stack with HE1000 and TH-X00. It definitely gives enough power to the bass department to put a smile on my face. You can also get into tube rolling if you want more bass. I am sure there are some great tubes out there that add great sub bass. Comparing to my other portable DAPS, I dont see any problem with the mj2 / gungnir stack. It is a landslide victory in terms of performance.