Audio advancement - why?

The way I understood the OP's question (or maybe the question I want the answer for) is why hasn't anyone built transistors that can sound as good as tubes to the ear? I don't think it's the matter of technology today, as we pretty much understand how transistors and tubes sound different. I don't think it's economics either. Imagine iPod with sound as good as good tube headphone amp. I bet whoever that can make transistors with tube sound will make a lot of money.

Actually there are transistor amps that do that, but you can count them on one hand with fingers left over. None of them employ global negative feedback- it seems that NF is a design element that has been holding advancements in audio back.

So far the Ridley Audio amplifier is the best example I have seen of what can be done with transistors. Last I heard, it made 100 watts and cost about $100,000 for a pair. There is a heater circuit for the output devices that makes the amp run every bit as hot as tubes. It is better than many tube amps I've heard.

I have yet to hear a class D amp come close, but that technology is still evolving and may yet bear fruit.

Jylee, you are correct. That was my original question. I also wonder sometimes that maybe SS is better than tubes currently - but maybe are we held back by our own "habits" of listening, such that anything other than tube seems "less" in our world!!
Semi went to the extent of size and Undertow mentioned the iPOD. When I mentioned advancement, I did not mean SIZE. Look at my evolving system - I am going from an integrated to a separate preamp and amp. I still cannot switch to iPOD or data-servers. Maybe they are as good as the current mediums I am using - but maybe I am biased to my current medium and that is preventing me from switching to digital files.
As for music as an art - I completely understand. In fact that is what I "try" convey to my non-audiophile friends. But remember if you can create art using more advance technologies, that can lead to betterment of art - why not explore it? Cave men used rocks, charcoal and other items to create art. Why did modern man come up with ink, paper and other stuff? Maybe SS audio has not been fully explored.
Atmasphere, I understand that humans did advance to Tubes. But looks like they are stuck there :-)

Milpai, true, we are stuck- for now. Believe it or not I would be the first to jump on the transistor bandwagon if I thought I could do it without sonic sacrifice!

If we listen to SS amps long enough humans will evolve to prefer odd harmonics :-)