I've ordered one of the Chinese 10 amp variacs. I could use it just for the preamp, or I could put it between the wall and my surge protector and run the whole system through it. The question is whether there's any benefit (sonic or otherwise) to running the whole system, including the ST-120, at a proper 117 VAC rather than the 108 VAC coming out of the wall. System is VPI Scout --> Bottlehead Eros (PH16x coming soon) --> ST-120 --> Troels Gravesen Fusion speakers, with a Bluesound Node 2i for streaming.
The wall voltage is 115 VAC now and it sounds amazing. Just wondering how to optimize for low voltage afternoons.