It's always good enough if you know your stopping point. If you ask for input to "upgrade", better get yourself ready for suggestions based on people 's personal experience/preference. I often say my akg Q701 is good enough but when I ask "what would be an upgrade?" the answer would be abundant.
For me, the TEAC is the "it" DAC for me. That I am 100% sure. Amp-wise, I am also done. 1 or 2 more HPs at the most then I'll be done too. The sound quality I am getting now from my combo is already to my ears "end game". I am not going to even think about paying more ridiculous amount of $ for the last 1% of SQ which I won't be able to distinguish. I am not one of those who will say "yeah, very minute improvement, definitely there, I can hear it blah blah blah..." I think that's bull schiit and self justification.
Looks like that's almost it for me too on the DAC and amp side unless I'm going to be spending over $1k on each. I might get myself a decent Sabre DAC and an OTL amp just to satisfy my curiosity then just like you perhaps a couple more cans