Thank you for the input, guys
I was in love with "Graham Slee 'Green' solo" before, but someone offer me a heed with an offer that I can't refuse. So if I buy a "Green" solo, I would think this as a small margin of upgrade, beside I heard Green solo works better with low impedance headphone such as my Denon D2000, and hardly synergies with K701.
Meanwhile, I'm starting to save money to get better amp/source later on, but I came back to the place where I got confused before.
Get a tube amp or get another solid-state amp?
Yamamoto HA-02 is currently my only preference for a tube amp, but I never heard anyone here using it with K701 (except 'kugino' above), and I assume it only works with Audio Technica headphones or even the mainstream HD650.
Darkvoice 337, is a huge beast - but since I tested DV336i and I lost my interest completely on Darkvoice product (tested with D2000), but will K701 scale well with this DV337?
Corda Opera was my dream amp, and maybe still...
but have anyone here, ever pair it with K701? does opera still introduce the warmth and close soundstage that offered by it's mini brother, Corda Headsix?
The rest, like BADA PH-12, Singlepower PPX3, WA6. It's way complicated - esp Singlepower & WA6 - where there is too much configuration/upgrade, which I think it's very essential and if I add the whole upgrade, that would cost me double the budget, not including a source.
Lastly, as I need new source, Ori introduce me to his new headamp product, which I heard from some head-fier here, that were very good, compared to his GS-1. So I done some research & study, the new headamp is an upgrade to the infamous OMZ v4 DAC. So anyone here own/ever heard OMZ DAC paired with K701?