Most of my Clear listening was on the following amps (usually paired with RME ADI-2DAC unless otherwise stated) THX-789, JDS Labs The Element w/El DAC, Monoprice THX-788 AIO, the iFi Nano Black Label (on the go). I agree with @Torq the Clears scaled easily with all of them. Also, I have tried them with the Schiit Modi3/JDS Atom/Magni in some shape or another. My Clears are currently on loan to @raindownthunda who is using a JDS Atom with a D10 DAC (please correct me if I’m wrong 
). So he can give a quick impression (sorry for calling you out, don’t worry, we are all friendly here…if not occasionally a lil grumpy ha)
Anyhow, I also think that the Phonitor could be Overkill if your only headphones are the Clears, if so I would go with Torqs advice regarding either the Cyan, RME ADI-2DAC, or just go full synergy with the Arche. Torqs advice has never steered me wrong (now my wallet might beg to differ ). Also, I recommend if able to try things before buying as much as possible, see if anyone is in your area etc. Or go to shops if available. Another great way is to dive into the forums preview program: