What is most important part of a system?

its the knobs

i've read, re-read, experienced and re-experienced, it is the speakers.
Put a great system on stupid speakers = stupid result
Put an average system on good or great speakers = it raises your system up!!

"maplegrovemusic
Anyone who stated source first in their list of importance please let me know what source will turn any speaker into some magical transducer . I really would like to try it ! Thanks, mike."

I build DHT components.  So IMO the source made the system sound the best.  I began by building a better preamp, settled on DHT preamp with no caps in the signal path and as good as it sounded, the source (DAC) I built made the sound something that I never experienced before.  So that is how I came to my conclusion source first. Same with the phono stage I build.  By better the components they created a sound that had details, could produce dynamic swings, micro/macro dynamics, separation, clarity, depth of soundstage (4D), placement, etc. that I never heard before.  Once that happened, I came to my conclusion that I everything else I tried over the years was to me chasing my own tail around.  Better speakers only improved what I was hearing.  I also came to this conclusion because when conducting auditions for other audio systems in those homes, those people after 30 seconds (yes 30 seconds) asked to purchase the components.  Recently had a person with very expensive Magico speakers and what I would consider a cheap DAC, SS around $2K.  OK sounding to me but after we switched source components, he heard things he never heard before.  It transformed his system.  It is the same change I hear in every system that we auditioned our components in, the source made the biggest sound improvement no matter the price of the speakers, Type of speakers, amps, cables, treatments, etc.

Happy Listening.   

I agree that it all starts from a source, but if preamp is not able to deliver it without veiling and distorting the signal, the source makes no big difference. Most mid-fi preamps are actually not able to transmit everything that a good source has to offer. Therefore for lower cost and budget systems I suggest a decent passive preamp like TVC for example. Start building the system from speakers to source. If everything below is up to the task then it makes sense to experiment with a source components.

The source is important yes BUT the heart and soul of any music system is the amp. Get that right the rest falls into place