Give it some time
I have just compared a fully burned in C3XP to my thrusty Playmate in vivid configuration for the first time afrer owning C3 for about 3 weeks. Tbh I wanted the Playmate to be as good or almost as good as the bigger brother. I was thinking I might keep the cheaper one and sell the more expensive one with litlle or no loss (had a good deal with preorder)
I have connected both of them at once to my work PC and started to compare. C3XP was with ballanced hp out, tried to volume match as close as I could. I was listening to my ZMF Eikon with suede Auteur pads.
I would say that the sound signature is rather close, neutral, but with added a little bit of a musicality to it. So, is it worth to upgreade? Unfortunately yes. Without any doubt. I cannot see any downside with C3, bass goes deaper, has more textures (or how to describe it), it is noticeable with bass guitars etc. Slam (not looking at the sub bass) is about the same, maybe a bit stronger with C3? Mids are just a bit more natural, bit more emotions here with C3. Highs have just a bit more information, but not more fatiguing. So they're close but the bigger brother does EVERYTHING just a bit better. I can feel the bigger sound stage, more air, better separation and better detail. Just a bit in everything. Well worth it in my opinion!
Not a scientific comparison, but it was so obvious to me (and my friend from work, he have had exact same thoughts), that after just 18 minute comparison I have made a sell add of my playmate and it is already gone.
Great amp, well done Burson!
I know a good otl amp will complement it with a wormer, more mid focused presentation, will probably buy one to change the flavour sometimes