VAC-1 is a higher current supply designed to improve performance from compatible products. In comparison to the included AC adapter there are several differences.
The standard supply uses a smallish (850mA) transformer, no filtering, and a longer (higher impedance) output cable.
VAC-1 uses a high quality 1.44A transformer with lower output impedance. It contains some mild filtering on both input(capacitor) and output(ferrite beads). In addition, it also uses a much shorter output cable for a lower impedance connection... the combined result is better dynamics and lower overall noise floor.
As was mentioned in a previous post, the rectification, DC filtering, and regulation, are contained within the product being powered.
In systems where you are trying to get the best performance out of the product, VAC-1 will allow this.
System matching/synergy is another "can of worms"...
In many cases, we are compensating for a trait of one product with the trait of another. For example... a bright sounding speaker might be paired with a warmer sounding component to get a better overall tonal balance.
Most find the VAC-1 to be an improvement, but I doubt it would help in this situation... I would look more at cable and tube changes.