Aleph Current Source

Hello everyone
Can anyone please advise me as to the feasibility of using a different MOS-FET in the ALEPH current source than is used in the output stage. I have lots of matched IRF460's and would like to use them as the current souce as long as the sound is not compromised. The 460's have an input capacitance of 4100pf which is more than 3X that of an IRFP240 or 244. The calss A output satge would use the 240 or 244.
Thanks