One thing I'd recommend you consider would be to snag a really good power regenerator.
When PS Audio released their P15 unit, I upgraded from my then-current P10 model and immediately noticed significant improvements in the bass, the soundstage and the clarity in the mids to highs, on both my PS Audio DirectStream DAC and my Mytek Brooklyn DAC.
As to your idea of spending on improvements nearer to the source, I'm in agreement with that concept.
When PS Audio released their P15 unit, I upgraded from my then-current P10 model and immediately noticed significant improvements in the bass, the soundstage and the clarity in the mids to highs, on both my PS Audio DirectStream DAC and my Mytek Brooklyn DAC.
As to your idea of spending on improvements nearer to the source, I'm in agreement with that concept.