I found what I'm looking for, and I can't imagine music sounding better than it does now. Any change I would make at this point would essentially just be preference rather than an upgrade, and frankly the upgrades at this point cost entirely too much to justify. Even if I did want more, I wouldn't be able to afford it, so I'm more than happy with where I'm at.

My current chain is Audio GD DI-20 outputting IIS --> Audio GD Reference 1 --> heavily modded Bottlehead Crack with great tubes --> ZMF Verite Closed Leopardwood.