+1
I agree. You are feeding a very good integrated amp / speakers with very inferior signal. This is very much limiting the output you are hearing.
You sound like you ran out of interest in the pursuit and feel somewhat let down. Am I reading too much into your words?
If you want to optimize your system, then an appropriate investment would be about $7K for a streamer and $7K for a DAC. I would recommend a used Aurrender N10 for a streamer. I’d have to do a bit of research on a DAC you could get… maybe a used Berkeley Alpha? Audio Research Reference DAC 9. These components would significantly boost the performance of your system to what it is capable of.