It is a great pity that this disc is not widely available now.
These are Arrau's 1960's recordings of the late sonatas.
He recorded them again in the 1980's, with the exception of the 106 Hammerklavier, which he did not re-record.
Happily this 1960's Hammerklavier is one of the great recorded versions of this sonata.
With many recordings of the 106 I find it difficult to hear a unity of structure and intent in the piece- however with Arrau this difficult and complex work of art finally made sense to me.
I feel that all his small choices are so felicitous, combining to make a unified whole. Arrau had a clear vision of this work and realises it beautifully.
Additionally this set contains one of the greatest performances of the Op 101 I have encountered.
For 109/110/111 I prefer his 1980's recordings which are unfortunatly only available as part of the very expensive Arrau Heritage box set. That box set also contains his 1950's Diabelli's btw, which is wonderful.