No wonder why hd650 was lacking in sound quality. So are you recommending a decent amp with hd 650 combo other than single focal clear headphone?
I touched on this topic in your other thread....
Basically you need to figure out which direction you are taking in this hobby before you decide between Focal Clear or an OTL amp.
If you go with an OTL amp you will be generally limited to headphones which are 250 ohms and up. Some examples are all ZMF dynamic headphones,Beyer DT series,T1,Sennheiser HD600/650/6xx,HD800. Im sure there are a few others out there that im forgetting.
Any headphone that is low impedance(0-100) will
generally not sound good on an OTL amp. There are some exceptions,but lets stick with the basics.
OTL amps also take tubes,which can be very expensive. Most amps come with a starter set of not-too-great sounding tubes. You will want to upgrade those tubes pronto. Many OTL owners,myself included,have spent more $ on tubes than what the amp itself cost!
My journey in this hobby has taken me from tubes,to solid state and then back to tubes. I have found my end-game headphone in the ZMF Verite closed and have a great OTL amp(Glenn OTL)to drive it.
I do not own a good solid state amp,so if for whatever reason I wanted to buy a Meze Empyrean,Focal Clear,Utopia or Stellia,HEDDPhone,etc....i would need to also buy a good solid state amp for them. My Glenn can drive some of these headphones well,but it is one of the few exceptions to the rule,and it really wasnt designed for these types of low impedance headphones in mind.
If you go with a Clear you most likely will want to dump the HD650 because youve already mentioned that you do not like the way it sounds thru your amp/DAC. Chances are it will not do well with other high impedance headphones either.
The Clear will be an easier choice,wont require you to learn about tubes and most likely will be cheaper in the long run. Just understand that if down the line you want a ZMF or T1 or HD800 you will be right back where you currently are,being underwhelmed by the sound youre getting out of your current set-up.