Aleph P rev 1.7

About 2 years ago I built the Zen line stage and have been very impressed with its warm sound. It reproduces strings better than any preamp I have heard, as a result I am now part way through trying to build the Aleph P rev 1.7 on my proto board so that I can easily better match the resistors and current source transistors.
Aside from close matching of the two signal IRF610s how tight a match do I need on the rest. Is it just a matter of adjusting the current source networks to insure that the same current flows through each signal mosfet or is there some other parameter that I should be adjusting.

This is a great forum I wish I had found it years ago.