This is a very old thread but I must post once more about how much I love my U70. I recently got a pair of Raidho c1. My solid state HK990 really sounded like crap, even though it had sounded so good with my Gallo Ref 3.5. The U70 introduce a smoothness, detail and high end extension. I had a hard time believing amps could sound so different. It is indeed about synergy.