As far as I know resistors also introduce colorations. TVC is just most transparent and neutral preamp solution I have ever tested. It lets you hear everything that your other components will allow. It doesn`t add any warm or cold colorations. If other components sound good it will sound good and if other components sound bad it will sound bad. It is dead neutral. I usually don`t go very deep about different technical theory's. I just listen and keep what sounds best. If sound matters most there are no cons with TVC. I am pretty sure that a good TVC can stand against any preamp prize no object. It seems that this is just superior technical solution. Just don`t place it near power amp because hum may appear. I suggest you to find some balanced Promitheus TVC. With balanced connections there will not any hum problem. These usually go for some $500 used and you can sell it at same prize if you dont`t like it.
TVC preamps: good or bad?
I was wondering what the advantages and disadvantages are of a TVC preamp? I have read elsewhere that transformers introduce coloration and aberrations in the frequency response, which is why we try to get them out of the output stage of valve amps. But ... what are the pros and cons of TVC preamps?