well, Ive been playing the piano for around 9 years, and a couple of years ago, I stumbled onto a book of Hanon exercises (60 exercies, to be exact.) The exorcise go for easiest to hardest (obviously), and If you can master all of the exorcises, you can MAYBE become a virtuoso pianoist. It took me about a year to learn all of the exorcises by heart. And, to keep my technique sharp, I practice the entire book EVERY day, which if you play it fast enough, you can go through the book in about in hour. But if you can play the ENTIRE book perfectly, you can play anything! Trust me! I spent an entire year learning nothing but these exorcises, and after I could play through them all, I was amazed by how well I could play really difficult songs! hope this helped

a virtuoso pianist has talent and you can become good quickly if you have talent.

If you can play any piece of music perfectly no matter how hard or fast it is and everyone loves your music, then you are a virtuoso pianist. It`s as simple as that, how long it takes you to get that good can vary. That goes for any type of musical instrument a person plays.

i agree on what sean said as long as u play them perfect..Chopin`s Dflat major prelude(raindrops) and Beethovens first movement of Quasi Una Fantasia are very sight readable..but is very musically challenging..making it in a sense a very difficult piece..and yeah..theres many arguements about Horowitz` opinion on warmups and piano exercises..i agree with what he said about being too mechanical..also..u really need a drive or a lot of inspiration..or else itll take forever...im not a virtuoso (yet)but i started learning piano at 6th grade..and i didnt become serious till i hit high school..and i leared a SHYT load of pieces and knowledge on music in one year and the 2 years that followed..im on my 5th year of piano(11th grade)..and i just finished Chopin`s Grande Polonaise Brilliante..and i`m finishing the Rach 2 piano concerto..im not close to Artur Rubinstein or anything..but i think im doin just fine no matter what anyone else says

Sorry, I don`t think 4 years is enough to become a virtuoso. I think you should keep working and keep studying with teachers. Maybe there`ll be a point when you`re really REALLY satisfied with yourself and you can stop taking lessons.