A mistake spending too much on amplification?

The Sixpacs are crazy good on their own, and unbelievable with the right preamp. I have Sixpacs driven by the companion AES DJH, and am continually impressed by the sound of the two together. Perhaps your Herron preamp is not the best match with the Sixpacs.

Narrod above states there are no night/day differences between various components, and any differences will be subtle. This may be true, but when components have true synergy, you'll know it! I personally believe amplification (including the pre) should be one of your absolute strongest suites (along with AC power and the room itself). Speakers and sources are secondary in my world.

BOA2 says,

"The fact is there are significant variations from one component to the next"

It is certainly a strongly held opinion by many but is not and, in my opinion, cannot be proven as "fact". I've been in this hobby a very long time and experience tells me that quality components are much more alike than different.

This does not mean that the differences aren't important. In many cases they certainly can impact how a given listener responds to a given component. Night/Day? I don't think so.

source first no matter what your amp are.

The behavior of either a piece of electronics or of a loudspeaker can be described in terms of its "transfer function". The transfer function is the sum total of everything the device does to the signal as it passes the signal on.

A purely electrical signal consists of variations in but two domains: time and magnitude.

But a loudspeaker's output has variations in five domains: Time, magnitude, and three dimensional space.

So a loudspeaker's transfer fuction is far more complex than that of a purely electronic component, and the loudspeaker therefore has much greater inherent opportunity to screw things up (which it takes full advantage of!).

Cutting to the chase here, in my opinion speakers make the most difference.

Duke

Mlauner writes "sources first no matter what your amp are." Not bad advice, and a very reasonable way to build a system. Start at the begginning and go forward.
I on the otherhand prefer to start with the best amp I can get or preamp and then work in either direction depending of what is weakest at any point. Myh view is the music is amplified right, first, and foremost the other parts can be brought into line sooner or later.
Neither approach is right or wrong just different approaches