Do you consider the psu caps in series with the output cap regarding the audio signal?Just thinking about the whole OTL thing. Mine, and all the rest of the single ended OTLs out there (apart from the only inverted OTL in the world) may be “output transformer less” but they are certainly not direct-connected to the speakers the way totem pole OTLs are, so the quality of the output cap will affect sound quality, just like an output transformer does, so FFS, bypass your output cap with summat decent.
In this case a cap multiplier with very little capacity caps like I use with the InvOTL or a HV reg psu like the Maida reg. for the output stage (keeping the TL738 as CCS) would improve the SQ.
How did you calculate the size of your output cap?