mbl 6011d or arc ref 3 or dartzeel preamp?

Neither the darTZeel amp nor darTZeel preamp are balanced -- the designer is strongly opposed to differential balanced circuits. Both the Version A and Version B darTZeel amps have XLR input connections, with the Version B XLR inputs using input transformers -- both versions of the amp are single-ended designs and merely feature XLR connections (as well as 50 Ohm BNC connections). The preamp likewise is single ended.

Just because something has XLR connections does not mean that it is truly differential balanced (most consumer gear with XLR connections is in fact NOT balanced). Again, darTZeel's designer thinks balanced circuits are a bad idea.

I use my Rowland Coherence II preamp, which is fully differential balanced, to feed a darTZeel, but I want to make an important point. The "Version 1" DarTzeel had XLR inputs, but merely for convenience for those who had balanced cabling - it was essentially a single-ended input (I can't recall what Herve did with the third PIN). The Version II, on the other hand, added input transformers at the XLR connections. They provide the advantages of noise cancellation inherent in balanced cabling, but they are still terminated into a single-ended circuit.

Herve advocates first the 50 Ohm connection, which was designed for use with his darT preamp (I have a set of 50 Ohm cables that I have used because my Rowland has a 50 Ohm output impedence, but I think they were loading down the preamp too much and I went back to balanced). If that is not possible, he suggests the single-ended inputs. The last choice would be the XLR inputs, which he does not prefer because, like all transformers, they put a lot of wire between the interconnects and the input circuit - he says the single-ended input is cleaner.

In any event, yes, the darT can be run from a balanced preamp, but the Version 2 is better set up for it.