A stupid question for which there's no sensible answer.

You are going to get so many answers your head will spin.  My advise is to first know what type of sound you prefer.  Second is to know why a product/component makes that sound that you prefer.  SS to tube for starters.  Then understand what company makes one of the products that makes the sound you like.  Last understand what makes that product sound the way it does.

One post says R2R tube DAC.  While I agree with that statement since my company makes one, we also have made non-R2R DACs that sound excellent but different.  Which one you prefer, that is the question.  I made a preamp that had 5 different output resistors.  Each resistor has its own sound.  Which one works in your system hell if I know - but with a turn of a dial you can choose what you like or even better for different recordings you can dial in the sound you prefer.  It is like swapping in and out a cable.

I am a source sound person.  I have to have the tone of an instrument first and foremost.  I need to hear the wood of the piano, the decay of the strings, and the emotion.  If the piano does not sound correct to me, then nothing else will.  To me, no other component can do that in my system.

Happy Listening.  

Not necessarily room treatments.  Just getting the right speakers set up right in the room which depends on where you are listening from.  You might not need room treatments to get good sound of you do that right. Can they make things even better once you do?   Of course.  But room treatments is not task 1.  

I can see that I'm coming from a deficit position in terms of comparing and contrasting both systems and individual components.
 I became an audiophile when, 2 years ago, I listened to my brother-in-laws old KEFs with whatever he had driving them. I fell in love and got some 20 year old References, along with a similar level 10 year old ss Musical Fidelity integrated amp. After a while, the speakers started hissing and distorting on certain piano, flute, and voice frequencies, so I went back to the drawing board and found a great deal on ATC 40ASCM V2s. Instant improvement and apparently a good match with my speakers--the UK sound.
But that's it. I've had no other opportunities to listen unless I wanted to stop in to dealers and tempt myself into either spending money I don't have or wasting their time. (I know. Most people don't mind doing this. I do). So I've only heard my system with one DAC -- Audioengine-- one type of cable (inexpensive) and two speakers. I don't know what's the room or what's anything, really. I did figure out a speaker placement problem (with help from another thread) when my new speakers were soundstaging unevenly.
So what is it all supposed to sound like? Which part is making it sound like X, Y, or Z.?
Is my amp warm or neutral? I know some of these conceptually--from reading online--but there's no substitute for literal experience.
This is why I appreciate all the responses I'm getting.

The most important component of a listening system is the listener.

The most important component of a listening system is the listener.

Very wise!

My best to you....