I had the astonishing privilege of being present at a live performance of Ikon of Light by John Tavener in Tewkesbury Abbey last night. This is the link to the Radio 3 recording (available for another 6 days)Â http://www.bbc.co.uk/programmes/b048ngnw
You need to listen to this in a very quiet environment on good headphones, if possible.
The Stabat Mater by the Estonian composer, Arvo Part, is also exquisite (and great material for  ‘Marriage of Sound and Breath’) as is his Miserere after the interval.