One limitation of using the tape out jacks is that they are located in the complete pre-amp circuit ahead of not just the volume control, but also the balance and mode (stereo/reverse/mono/left/right) controls. Those controls are the very reason I have an ARC LS-1 (in addition to an EAR-Yoshino 868L), and I wish contemporary pre-amps has them, as well as a phase switch. Ralph Karsten includes the latter in his Atma-Sphere pre’s.
All "non-essential" controls were jettisoned in the purist pursuit of creating the shortest signal path, and pre-amps and integrateds containing them have become viewed as compromised, non true high-end designs. Well la de da ;-) .