After i spent sometimes, trying this and that..i finally found the best portable rig to come with my HD650. The best i have listened so far (from any portable i currently have) is using combination portable rig of Glacier + CLASdb + Ipod Classic. The sound quality is i believe above my previous desktop rig which was Solo SRGii + Dacport LX. The synergy is all there and is very satisfying result of sound quality. The other simplier combination is Ipod Classic + ALO International. This also can drive HD650 with ease, the sound is good but not as good as my fist combo i mentioned.
I compared using combination of CLASdb + International (using bal2bal connection) VS CLASdb + Glacier (using m2m connection), the sound quality was almost on par..but detailing and clarity i still prefer the later. The dynamic character of Glacier i think is a perfect match with HD650. What a lovely combination really.
My two favorite rigs to drive HD650:
Source : Ipod Clasic 160GB with WAV File
HD650 cable: Double Helix Cable 24AWG Copper