What sounds best integrated or separates?

On a theoretical level -- neither need to sound better "in regards to musical involvement musicality tonal balance etc" as you note.

But... we are speaking about commercial products. So: it's easier to compromise in an integrated -- common PS, one box... (OTOH an integrated doesn't require IC wire...)

In practise, and speaking about mid category UPWARD the best results are usually obtained with separates... both from a practical (more choices) and financial point of view...

Exceptionally, you find integrateds which perform as well as -- or better than -- separates. But the prices here are unexceptionally and invariably high.

At the lower end (i.e. reasonably priced) products, integrateds rule IMO for a number of reasons. Not least is, if you're on a budget you don't want to spend money on extra chassis (very high cost), extra ICs, etc...

So stick to yr tube integrated. Cheers

Integrated amps are generally more limited in power (to keep down costs). Separates are of course more expenive but perform far better.

As Greg says, it is very price dependent. A high-end integrated will better budget seperates.
I would take a Creek Destiny integrated over a NAD 162 preamp 272 amp any day.
Not knocking NAD, they make fine products, but are for the more budget minded.