A mistake spending too much on amplification?

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

Do you still have both the Sixpacs, & the DNA-125? If so, you might want to keep them both given their reputations. It's puzzling that they wouldn't sound quite different from one another tho.

But I don't know your speakers, or how efficient they are, or how good they are. Or your cables, source components, etc. What.....are you trying to accomplish, sound wise?

"Source first" reminds me how much I hated my Linn Sondek LP 12.

I think a much better theory is that your system will only be as good as its worst component.