They are Triple A with Allyssa Pram (voice) from Whanganui High School and Angela Wu (flute) and Advina Wu (piano), both from Wanganui Collegiate. The group also won the Wanganui Music Society award for the Best Group featuring a vocalist.
No Strings Attached comprise Luke Squire, Sarah Wright, Isaac Patterson (cornets), Ethan Mancer (Euphonium) and Caleb Squire (percussion) from Whanganui High School.
The group also won one of two KBB Music awards (for a group showing excellence in wind, brass or percussion).
The Kimslee Trio are Yeju Kim, Emily Kim and Sun Jae Lee (piano) of Wanganui Collegiate School.
2 Crotchets and a Quaver are Abby Squire (voice), Anna Zhang (violin) and Ahimsha Saravanapaven (piano) of Whanganui High School.
The other KBB Award went to No Strings Attached and Les Trois Teaux - Hannah Kemenater (flute), Ethan Gillespie (saxophone) and Rada Punnarujawong (piano) from Wanganui Collegiate School.
The Adjudicators Award went to Guitars-a-Fire with Cameron Walker, David Dale Jack Fawthorpe, Noah Payne (guitars) of Whanganui High School.
The Whanganui Branch of IRMT award for Most Promising Junior Group went to The Buzz Rolls with Harvey Hughes, Chester Nevil, Jonathan Stolk (percussion) of Whanganui High School.
District organiser Ingrid Culliford said adjudicator Anthony Ferner was very complimentary about the overall abilities of the young contestants.
Ferner said The Millennium Trio gave "an absolutely spectacular, stunning and very cohesive performance".
"His comments overall focused on projecting shape, dynamics and character, and he had some very pertinent comments to make for the many vocalists who took part, about language, vowels, and sustaining a line," said Culliford.
"He enjoyed the range of groups that were presented and the variety the brought to each of the three sessions, describing each session as "an enjoyable concert in its own right".
Culliford said it has been a great "festival" of chamber music making, with participants from all but two of the district's secondary schools and home educators.