My take is: it's important to have a great amplification to speaker foundation. And sources become increasingly more important after that, the right foundation of amp and speakers will show you so much that is wonderful--and not so wonderful--in source components. After that it's fine tuning. Clean electric, isolation control, cabling--all became important to me once I got the amp-speaker and component foundation selected and perfected.

Percentage. . . there are so many variables (new, used, vintage, SOTA and combinations etc.) that I won't throw out numbers.

To a new listener/enthusiast an important question or three is/are: tube or solid state, vintage or new production, digital or analog or both, and perhaps patient or impatient.

Also: what music one predominantly will listen to will influence choices. I'd like to say that a great system will treat any genre with equivalent excellence, but in the world of practical selection and daily use a system that has one dancing and head banging to rock or other amplified material is one that may not showcase classical, folk or jazz etc. in the best light, and vice versa. (Just my experience, I'm beginning to realize this more as time passes). Keeping in mind what will go in and come out of the system can help pinpoint the system one wants and needs.

My first instinct is 33-33-33% source-amp-speakers, but then I think of a close friend of mine that has a Stanton DJ turntable, a Denon consumer grade receiver, and Polk T50 towers. His system sounds amazing. He spent less than a grand on all of it, about an equal amount on DIY room treatment, and set his room up correctly.

My advice to someone starting out in the hobby is not to get caught up in the hype and FOMO. Give yourself a budget, spend half of it on getting your room set up right, and the other half on the best gear you can afford from the used market. Then enjoy the music.

I'd just like to add that I understand the love and "need" for treated rooms, but not everyone can install a system and also install room treatment. I've found many a great system in a treated room, and many a great system in untreated spaces. Either route IMO can have stellar results.