Will McIntosh C2600 tube preamp solve my problem?

"Also, several respondents are referring to 802 D3 and I have 802 D3 speakers."

Sorry, my post was a typo. The Stereophile review was for the 802 D3. 

What are you using for the source component?

Ah, well, then the 2600 might be a great pre-amp option.  You should be able to find a lot of nice power amps to drive the 803s. 

A dac is a digital to analog converter.  If records are your only or primary source you likely don’t need to pay for that feature.  However, if you are using an old CD player and it has a digital output you may find a modern dac offers an improvement.

Your Rotel RB 1590 is 350 Watts per channel which is more than enough power for a large speaker like your 802 D3’s.

 The RB 1590 is not specified as a dual differential amp so the XLR inputs are likely just a convenience. So a preamp with RCA inputs and outputs will work.  However, there is one problem.  The input impedance via RCA is a very low 12k ohms while the XLR is 100K.  Most tube preamps will be compromised seeing 12K ohms.  So that means a preamp with XLR output connections would likely offer the best performance.  Preamps so configured are more expensive plus you will need a quality set of XLR cables to connect to your RB 1590.

Does this help or add to the confusion?

Don't understand the question of "what is my source component".  Can you be more specific?  Sorry for my lack of knowledge.

Don't understand the discussion of "XLR output connections", but yes, it does help because I can research what you mean and ask my local dealers.