I can't freaking decide on an amp for these guys! Please help! Here are my requirements: * I've read the HD650 is very responsive to different amps. I want an amp that will not let me down with these guys! * I want it to be able to drive my Grados, too. So that eliminates Bottlehead Crack, I believe... * Tube pre-outputs are a plus. * Under $350. EDIT: My DACs are Modi and an Aune T1 (on the way). I would just use the Aune to power the HD650 but I want an amp that powers both headphones, and I've heard the Aune is no a no-go for Grados. Any suggestions? My current contenders are Asgard 2 and Project Sunrise II (BATTLE OF THE SEQUELS!) But would Project Ember work as well? Thanks for your suggestions. Cheers and happy listening!