Replacement of IRF730 for Sonic Frontiers SFL-1

[Tubenstein]

My friend and I also own a Sonic Frontiers SFL-1 and these are the questions we want to ask:

Is any MOSFET out there considered as an improvement of IRF730 for
direct replacement. My Sonic Frontiers SFL-1 hybrid has a IRF730 in
there.

What about 2N6768 and STP7NK40Z?

The Sonic Frontiers actually based on the design of Curcio Daniel II,
and Curcio has MTP3N40 for the same position instead of IRF730. I have
no idea the sonic character between both MOSFET. However, it should be
something out there better than both since transistor technology is
very mature today. Should be more linear, less noise and lower
distortion than the IRF730 and MTP3N40! Or you suggest stick with either IRF730 or MTP3N40?

Any suggestions are welcome!