why wasting 2SK170 , when with two-bjt-CCS you have very nice CCS , with superior Tempco . with R9 set 20mA through input LTP ( exactly 9V4 across R3 )both R12 and R25 are influencing Iq and offset ; start with R25 at zero , trim R12 to desired Iq , then fiddle offset with R25 20mA type is good ; they're operating here at 5mA ; nice value , considering both internal resistance , tempco and noiseQ8 ? base of Q8 via R24 and base of Q5 via R2 are connected to neg PSU, via R21 put some little heatsink to Q8 ; Q7 is maybe just warm ; difference between BD140-10 and BD140-16 , same as between 556B and 556C are just in Hfe ; do not even bother ..... tell me more .....