I don't have personal experience in comparing the Promitheus TVCs to Bent Audio, nor do I have enough personal experience with resistor-based passives to say anything particularly insightful about differences in sound quality in comparison with transformer-based passives. However, I do have extensive experience with the Promitheus dual-box EI-core TVC and the new double C-core dual-box Signature TVC in my SET audio system.
The Promitheus EI-core TVCs are an excellent value with very good sound quality, but Nicholas Chua has really raised the stakes with his new line of C-core based TVCs. The C-core TVCs have more fullness, weight and body to the music and they give you an uncanny sense of presence. If you want to see what a TVC can really do, I can heartily recommend the new C-core TVCs in the Promitheus line of products. The Signature TVC is a force to be reckoned with that, in my audio system, competes very effectively with high end active preamps.
The Promitheus EI-core TVCs are an excellent value with very good sound quality, but Nicholas Chua has really raised the stakes with his new line of C-core based TVCs. The C-core TVCs have more fullness, weight and body to the music and they give you an uncanny sense of presence. If you want to see what a TVC can really do, I can heartily recommend the new C-core TVCs in the Promitheus line of products. The Signature TVC is a force to be reckoned with that, in my audio system, competes very effectively with high end active preamps.