For unbalanced signal I have a 6-channel bf862 preamp by Juma (with bf862 output buffers included), about 8dB of gain:
https://www.diyaudio.com/forums/pass-labs/254190-options-5-integrated-amp-2.html#post3922510
https://www.diyaudio.com/forums/pass-labs/254190-options-5-integrated-amp-3.html#post6158659
if I made LUdef could I drop the ZM's jfets and also drive the original M2 transformer with ~15dB of gain? (to explain the latter: even with the preamp I try to keep my amps in the multi-channel setup in the same ballpark gain-wise if possible). Is driving say a 16inch long cable connect in front of the naked transformer an issue?.
https://www.diyaudio.com/forums/pass-labs/254190-options-5-integrated-amp-2.html#post3922510
https://www.diyaudio.com/forums/pass-labs/254190-options-5-integrated-amp-3.html#post6158659
if I made LUdef could I drop the ZM's jfets and also drive the original M2 transformer with ~15dB of gain? (to explain the latter: even with the preamp I try to keep my amps in the multi-channel setup in the same ballpark gain-wise if possible). Is driving say a 16inch long cable connect in front of the naked transformer an issue?.
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Linked preamp is not suitable for driving heavy load as transformer. We need very low output impedance preamplifier like Iron Pumpkin, Salas DCG3, ACP+.
Many headphone amplifiers could be suitable.
I've just finished one set, for Buddy of mine
custom cases made by him (powdercoated Al) with my nudgenudge about necessary demands (size of hsnk)
overall dimensions dictated with acquired SH heatsinks
not a problem as they go under short speaker stands bellow his 15" Tanns....... even if I more like form factor of 4U/400 long Modushop htsnk
as always custom made Donuts and custom made chokes (4m7H, 0R15), high nickel Cinemags, Neutrik jewels at back
pics, post 1 of 2
custom cases made by him (powdercoated Al) with my nudgenudge about necessary demands (size of hsnk)
overall dimensions dictated with acquired SH heatsinks
not a problem as they go under short speaker stands bellow his 15" Tanns....... even if I more like form factor of 4U/400 long Modushop htsnk
as always custom made Donuts and custom made chokes (4m7H, 0R15), high nickel Cinemags, Neutrik jewels at back
pics, post 1 of 2
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Nice amp builds ZM - you're probably too modest to say so yourself! 
Is that very much?
Is that very much?
Amazing. I love the cyberpunk look! I see that you used xlr inputs... how is balanced input realized in this amp?
I had to put a work stop on mybuilt as I was busy interviewing for an industry job in 'Pass Country'. ;-) Since I am now in 'wait mode' nothing better to get my mind off things than resume the build!
It's almost ready for testing! A couple of power wires and I m ready to go.
Since traces run near the edge of pcb, I used 3/8 tall (~9mm?) nylon standoffs with nylon screws and washer to fasten PCB to heatsink. Then, I am also relying on TO3p solder joints to hold the PCB via their metal screws. I had to enlarge the holes of said to3p on the pcb to make my life easier.
I am also giving detail pic on how I interfaced the lu1014 to the board. I think its a good solution easy to do.
Since traces run near the edge of pcb, I used 3/8 tall (~9mm?) nylon standoffs with nylon screws and washer to fasten PCB to heatsink. Then, I am also relying on TO3p solder joints to hold the PCB via their metal screws. I had to enlarge the holes of said to3p on the pcb to make my life easier.
I am also giving detail pic on how I interfaced the lu1014 to the board. I think its a good solution easy to do.