If Benchmark DAC1 and Cary 303/300 didn't have any tweaks at all. Then Cary + Nordost Vishnu would give little better sound than DAC1 + Nordost Valhalla. But I would still spend the money on the power cord because once you add vibration isolation the DAC1 becomes better than Cary. The more tweaks I added the more veiled the Cary became, but the DAC1 just kept improving in smoothness, transparency, low-level detail, bass and soundstage size.
It is better to plan your future purchases instead of only think one move ahead. You keep the power cord your whole life so it's the better buy even if it doesn't give you the most for your money right away.
If you tone down excessive brightness with veiled electronics you get the illusion of more low-level detail, but the difference is very small. If you plug in a stock power cable into a high-end source and it sounds smooth and musical, then the source isn't working properly. If you get harsh, bright, edgy and fatiguing sound, then the source is working like it should. If you fix the vibration, EMI and AC problems then all that brightness turns into warmth + low-level detail.
An unshielded power cord doesn't fix any problems, it just colors the sound to the worse to make it more listenable. I prefer to veil the sound with the Valhalla power cord instead of blurry DACs or tubes because the power cord is already in the path.
Using upsampling is better than adding a power cord because it doesn't reduce low-level detail, but it wasn't enough smoothness to me, AES/EBU does only 192kHz. I had to add a Valhalla band-aid that removes a lot of low-level detail to make it sound musical, I like the Valhalla because after I modified it thinner I get only little less low-level detail than neutral, but also faster sound than neutral, everything sounds kind of hollow. It makes the power supply work very badly, but I like that flavor, that's why I would buy the Valhalla before any other components.
