Twl has a very good point. It is my belief that the reason that some passsive attenuators sound thin and lacking in dynamics is because they fail to present a high enough input impedance to the source and/or low enough output impedance to the power amp. It's all about impedance matching.
An active preamp can much more easily present a high input impedance and a low output impedance, and should therefore be more system independant.
I have no experience with transformer coupling, but if it solves the impedance problems then I can see how it could be the best of both worlds ... the transparency of a passive attenuator with the impedance matching (and hence the dynamics) of an active preamp.
I'm just too much of a tightwad to try out my theories !
An active preamp can much more easily present a high input impedance and a low output impedance, and should therefore be more system independant.
I have no experience with transformer coupling, but if it solves the impedance problems then I can see how it could be the best of both worlds ... the transparency of a passive attenuator with the impedance matching (and hence the dynamics) of an active preamp.
I'm just too much of a tightwad to try out my theories !