retunable piano for max (tenney project)

hi all

i'm writing to ask advice on software. i'm afraid i've been out ofthe loop for sometime, and what i'm going to ask'll be very basic.

i'm going to make some new versions of jim tenney's spectral canon.
i know most of you will know that clarenz barlow programmed a version
(for synclavier, i think) which didn't stop on the final chord of the
original, but saw the process out. jim added this to his oeuvre as
spectral canon (extended).

in around 1998, jim sent me equations for a new version and i made a
test of it with max and an old proteus. it didn't synch properly - a
combination of my poor programming, 16-note midi and the processing
speed of my old mac - but jim was nevertheless interested in the
piece. i'd intended to sort it out properly, but other stuff got in
the way.

anyway, i was very lucky to get the chance to do a little work on it
with him again in dublin last spring. i did some sketches in flash
(dots on a screen showing the shape). we thrashed out the maths (jim
thrashed out the maths) for the four permutations of the original and
he was very excited about it and looking forward to hearing all of
the realisations, but unfortunately, i didn't get it done in time for
that.

here's my question: i'm using max/msp on a mac, and obviously i need
to hook that to some retunable piano sound, but i've only been
working with sinewaves generated from inside for the last few years.
what would you guys suggest? are there softsynths or similar?

thanks
ciarán