Amp vs Preamp which is more important?

I think you phrased the question well, acknowledging the interdependence of the two. 
 

I have to say the preamp. It takes the really small signal and brings it up to the level the brute can handle it. The preamp is the heart of the system… it brings consistent sound to a system. 
 

Over the last fifty years of my pursuit of the high end, the preamp was generally my most expensive electronic component. I would keep it the longest, then make it the biggest jump in quality.

In general, all my electronic components are in the same price range now (my system is shown), with some variability. In general I would recommend all components would be roughly in the same cost category: preamp, phono stage, DAC, amp, streamer and turntable. But if there were a bias, I would lean towards more investment in the preamp.

If I upgrade soon, it would be my Audio Research Reference 6SE for an Audio Research Reference 10SE (yes, I know that does not exist yet. But the reference 10 does).

@tattooedtrackman 

The reason I am not upgrading to the Reference 10 right now is because it is not a financially reasonable thing for me to do. But if I correctly envision my financial status in a couple years, I may be able to do it. On the other hand I am very happy with my Reference 6SE. Improved financial condition… plus incentive of an even better two box solution might be the level of enticement I need.  

@localnet

Great experience for you. Our journeys to audio nirvana is individual. Our systems are composed of a bunch of components in our audio space. We have different values and different homes. It is a journey that we must make ourselves… but external input can be helpful… but not always.

There are gear oriented folks that really enjoy swapping out stuff. There are a lot of ways to enjoy this pursuit. Me, I do slow methodical advances based on lots of research. Each component has had a huge amount of reaseach put into it… and the expenditure was at the max I could make. After 50 years, I couldn’t be happier at the outcome. Each of the last dozen purchases have had exactly the right effect and result in my system. I guess 40 years of intent study have had their value.