If going to make a comparison between and exchanged device, I have always found it best to let the New Device have a few weeks of usage, with regular periods of experiencing the device being used. A month is a period I would suggest is enough to allow the impression to be made, that is formed on a reasonable time spent experiencing the device in use.
For myself, it usually works for the best, when the device is not analysed, but let be and able to present music. The way the music holds the attention and the replays are conjured up as after thought, is usually an indicator something is new and forming an attraction.
If noticeable changes are becoming detected from the produced sonic, then the likelihood is that a Run In is occurring and the device is becoming more coherent in how it is presenting.
When returning to the A/B comparisons of old vs new, there will be plenty to suggest one of the devices is worthwhile being maintained in the system in place of the other.
Being an Audiophile is to be one who has a enthusiasm to enjoy listening to music, achieving this place is easy, and for many has proved to be quite an addiction.
To extend the enthusiasm to attempting to enjoy music replays through the usage of electronically designed equipment, has the potential to leave an individual dis-heartened at times, but there is a place that can be found, that centres around the system created is enough to substitute the desire to experience music being reproduced from other means.