if you have other questions , let me know, I'm here for these.
regarding the 2200uF cap , it's necessary using t1,t2,t3,t4 and t5, t6, t7, t8.
Using hand mached transistors needs this cap, because without this cap the current of these two groups of transitors are unbalanced.
Can be avoided this cap changing these 8 transistors with a IC super mached trasistor pair.
Discrete mached transistors were used because at that time there were no IC super mached transistors in the market for this use.
Can be used the complementary of the same IC super mached pair used in SSL 9000 preamps , it's the MAT03
http://www.analog.com/static/imported-files/Data_Sheets/MAT03.pdf the amek 2500 with this IC will be the same very low noise of the SSL 9000 preamp..............not bad.....I think
moreover it's necessary adding a diode to D5 change r12 and r11 values.
soon the schematic modified.