This prelude is ABRSM grade 7. ABRSM grades vary between 1 – elementary to 8 – advanced; however, grade 8 does not really mean “virtuoso” repertory which is well beyond the grades. You can get more information here:https://pianoforum.net/smf/index.php/topic,1947.msg15391.html#msg15391(ABRSM grades and their importance)Have a look at these several threads where ABRSM grades are given to several pieces from the standard repertory for comparison:https://pianoforum.net/smf/index.php/topic,5323.msg50895.html#msg50895(Grades for all Inventions, sinfonias, French and English suites)https://www.pianoforum.net/smf/index.php/topic,7303.msg72931.html#msg72931(grades for all partitas)https://pianoforum.net/smf/index.php/topic,2958.msg25879.html#msg25879(Easiest Chopin pieces – grades 4-5-6)https://pianoforum.net/smf/index.php/topic,6957.msg69287.html#msg69287(Chopin pieces grades 7 & https://pianoforum.net/smf/index.php/topic,6954.msg69289.html#msg69289(Chopin Polonaises, graded)https://pianoforum.net/smf/index.php/topic,3827.msg34579.html#msg34579(grades for all Chopin preludes)https://pianoforum.net/smf/index.php/topic,3943.msg35797.html#msg35797(grades for all Chopin waltzes)https://pianoforum.net/smf/index.php/topic,5273.msg50900.html#msg50900(grades for all Mozart sonatas)https://pianoforum.net/smf/index.php/topic,1314.msg14339.html#msg14339(grades for Grieg’s Lyric pieces)https://pianoforum.net/smf/index.php/topic,4046.msg36920.html#msg36920(grades for all of Haydn’s sonatas)https://pianoforum.net/smf/index.php/topic,5027.msg47777.html#msg47777(grades for Brahms pieces)https://pianoforum.net/smf/index.php/topic,5143.msg49023.html#msg49023(grades for Mendelssohn’s SWW).https://pianoforum.net/smf/index.php/topic,2911.msg24991.html#msg24991(grade 7 sonatas)https://pianoforum.net/smf/index.php/topic,3721.msg33399.html#msg33399(grade 4 – 6 repertory)https://pianoforum.net/smf/index.php/topic,3786.msg34321.html#msg34321(grade 6 repertory)Of course, grading is to a large extent subjective and not very important after all. Have a look at these threads where the subject is discussed at length:https://pianoforum.net/smf/index.php/topic,3472.msg30727.html#msg30727(grade requirements for different institutions around the world)https://www.pianoforum.net/smf/index.php/topic,6438.msg99437.html#msg99437(what are grades – comparison with martial arts belts)Finally, don´t miss Torp´s spreadsheet, where he has summarized most (if not all) of the information on grading in the forum:https://www.pianostreet.com/Graded_Pieces_All.xls(Torp’s graded pieces excel spreadsheet)Best wishes,Bernhard.
Can someone please tell me what level is Chopin's nocturne in B (opus 9 no. 3)? That piece seems really obscure compared to no. 1 and 2.