Agreed. My 1st class D amp I bought about 6 years ago, a Class D Audio SDS-440-CS, came with a 28 day in-home free trial. It sounded very good straight out of the box but it kept improving in sound quality well past the trial period. I think its important that prospective class D amp purchasers are aware of this 'break-in period' which may last up to several months.
I'm still not even sure if the class D amps require a break-in period or the listener/buyer actually needs an adjustment period to get use to the sound of the amp. From my perspective, I noticed immediately that the amp was a big improvement over the good quality class AB amps I had previously used for decades (Adcom, Aragon and McCormack) that was pleasantly surprising in its quality but I also sensed it was a fundamentally different listening experience that I thoroughly enjoyed.
It was initially hard to describe what specifically the sound qualities were that gave me a sense of being fundamentally different but the more I listened to the new class D amp, the more it became apparent exactly what these qualities were. The major sound differences I identified were an extremely low noise floor that gave the impression the music was emerging from an inky black and dead-quiet background, improved bass impact and dynamics, a more neutral overall presentation that also was more detailed from top to bottom and a smoothness to the midrange and treble response without brightness or harshness and the ability to portray a solid 3D soundstage that's at least the equal of my previous class AB amps.
All of the above just further supports our advice for auditioning any amp one's considering in their home and system prior to buying when possible. I just wanted to let prospective class D amp buyers about what to expect.
Later,
Tim