You just cannot buy a pre-amp independently and expect everything to work when you connect that to a power amp. The least that has to be considered is the output impedance of the pre and the input impedance of the power. The latter has to be much much greater than the former for the units to work well together.
Can anybody comment on effect of tubes on the common wisdom that power amp input impedance should be at least 10 times the output impedance of the pre amp.
I am sure there are a few other factors that should come into play. You have listed active pre-amps. In case you want passive, then there are a few things more one needs to consider. Passive pre part is discussed in my amp thread.
Which power amp are you thinking of pairing your pre with? I know you were looking for a power amp. Did you get one?