She's alive!
Finally completed my LC kit with the following component swaps and modifications:
1) Installed a Hammond (1182M15) 80VA Torroidal Transformer [barely fits] (w/500mA slo-blo fuse).
http://www.hammondmfg.com/1182.htm
2) Replaced C305 & C306 4700μF 50V capacitors with genuine United Chemi-Con (16M6799).
3) Replaced LM317T/LM337T (Q301 & Q302) with genuine Fairchild regulators (58K8936/58K8937).
4) Replaced LM317T/LM337T R2 1KΩ resistors (R306 & R308 [R308 on schematic is mislabled] ) with two parallel Zener diodes (18C6023) in each position for lower resistance and safety.
http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/870#post_7930416
http://www.acoustica.org.uk/t/3pin_reg_notes1.html
5) Replaced the LM317T/LM337T Cadj capacitors, C308 & C311, with genuine Sprague 10μF tantalums (30C8841).
6) Replaced C103, C104, C203, C204, C313, C314, 470μF 25V capacitors with genuine Panasonic FC (80K8337).
7) Replaced C101,C102 & C201, C202, 1.5μF 200Vdc and 0.022 μF 600Vdc input caps, with SoniCap Gen I (cheap & good enough).
http://www.soniccraft.com/product_info.php/gen-sonicap-15-uf-200vdc-p-417
http://www.soniccraft.com/product_info.php/gen-sonicap-0022-uf-600vdc-p-404
8) Replaced opamp with genuine Texas Instruments LM4562HA with TO-99 to 8-pin DIP Adapter and TO-99 heatsink.
http://www.ti.com/lit/ds/symlink/lm4562.pdf
Worked perfectly on the first smoke test - and sounds great!
Thanks go out to the many "BlaBlaBla" posts earlier in this thread for sharing his technical knowledge, experiments, troubleshooting and suggested upgrades. Kudos!