I'd like to buy a couple amps for my DT990 and K702's. I've ordered a HeadAmp Pico amp/DAC and am trying to get a RSA P-51 for portable amps. I've replied to a couple FS listings but no one returns my PMs. I'd also like a good desktop amp for about $500 or less to use at work. Anyone have a good desktop amp that would compliment these pairs of cans? Yes, I'm new.