If you add a different thickness power cord after the apartment wiring it will make it sound less neutral, but the flavor may sound better to you. If you keep mixing different thicknesses of power cords it will sound messed up.
When I bypassed the power conditioner and plugged everything to the wall it sounded cleaner, it was more relaxing to listen to because there wasn't a mixture of wire thicknesses in the signal path. The Premier Power Plant has 10awg wiring from the regenerator to the Quintet on the back, and the Quintet has thick copper bars. I could hear the mixture and it sounded like a mess. But the Premier also cleans AC noise so I got more low-level detail.
If you are going to mix different thicknesses, use as short power cord as possible.
Based on my experiments, it's better to put the thicker power cord before the thinner one. So you make the signal path thinner and thinner. I have modified my Valhalla power cords thinner (16awg) than the apartment wiring (14?) and I get more low-level detail.
The power cord that made the biggest difference was PS Audio xStream Statement 6awg. It removed EMI because of the shielding, but it also made everything slower and muddier which gave the illusion of bigger bass. Since it was a lot thicker than the apartment wiring, it removed a lot of detail. The bass signature was very easy to hear.
So if you want the most low-level detail you need to use the same thickness as the apartment wiring. You also need the same brand to get a consistent sound. And then you need to wrap them all in ERS Paper. It's going to sound better than aftermarket power cords unless you like the flavor of them.
I like the flavor of Valhalla power cord because it makes it sound smooth and open which gives the illusion of transparency and bigger soundstage. The longer the Valhalla is the more of that coloration I could hear. All aftermarket cables make it worse than the neutral apartment wiring. Its all about the flavors. Cheaper electronics have worse power supplies and they are more sensitive to different flavor of AC power. If you like how a power cord sounds, it is better to spend money on it than more expensive electronics.
I like Benchmark DAC1 because it has more brightness and has a narrower soundstage than other DACs. But since the Valhalla gives smooth and open sound with a huge soundstage, it's a perfect match. I don't think there's a better match for transparency.