There are other couplings of the Grieg and Sibelius quartets, most notably from the Emerson and Guarneri quartets, so this 1997 recording from the New Helsinki Quartet faces some competition. I haven't heard the other recordings, so I don't know how the New Helsinki compares. I do have a recording of the Grieg quartet perfomed by a group anchored by Truls Mork (Grieg: Cello Sonata, String Quartet), and it's a very passionate reading. I actually prefer the New Helsinki's approach a little bit more; it's very intense, very committed, but not quite as overtly emotional. The music lends itself to pushing the envelope, so to speak: it contains Norwegian folk material and is recognizably Grieg, but in no way does it contain "too much folksiness," a concern the composer expressed prior to embarking on the quartet. On the other hand, Grieg wrote music that people could identify with and would listen to, therefore the distinctive national flavor is very much embedded in the score. Anyway, it's wonderful music, one of my favorite things from Grieg.
The Sibelius quartet (1909), subtitled "Voces intimae" (Inner Voices), is the only chamber music from the composer's mature period. It was written between the third and fourth symphonies and has the distinctive sound of Sibelius's orchestral works. It's not as immediately accessible as the Grieg quartet, which was completed thirty-one years before, but it's a fascinating work, filled with imagery that's almost visual as opposed to the adapted folk material of the Grieg. It's a perfect companion to the Grieg and the producers were wise to have this quartet, which is a much "cooler" temperature, open the program.
The New Helsinki Quartet was formed in 1982 and is made up of mambers of the Finnish Radio Symphony Orchestra. Their affinity for this music is self evident and the recording quality is A+. Discs are offered at under five bucks from amazon resellers - a great deal. Five stars.