Hi, if I had to upgrade desktop-speakers today, I'd go for these (causing a wave of excitement over here)
I don't know if you have any size constraints or not? Or if you need the speakers to be portable? But i see you use ATC active speakers. I am using Mackie HR824's at my computer and they sound fantastic. They are also active and have a separate amp for each driver. There is also the HR624 which has the 6" woofer and i am sure that sounds fantastic as well. I saw a very nice pair of HR824's for sale on ebay for around $600 just the other day. Definitely worth a check out for very high quality near field listening i feel.