Audio Research CD8 Break In?

[kingm88]

I purchased a second hand ARC CD8 last September and a S/H ARC DSI200 which had a brand new circuit board so was essentially a brand new unit.
I don't know the age or history of the CD8 but as it was a few years old I presumed it was well run in.
It did have an noisy transport issue where the cd platter must have slipped and on some cd's the cd was rubbing the dust cover, but I fixed that.
Anyway so I have been trying to run in the amp over that last few months using a secondary source and must have racked up near enough the recommended 600 hrs.
However listening to the CD8, I felt the sound wasn't ever quite right. I thought it sounded okay but seemed flat without much depth and tonally a bit off. I was never wowed by the sound. I even bought a set of new tubes but TBH it didn't make that much of a difference. I just put it down to the amp not being run in properly.
I then played a couple of flac files direct from a laptop and was a bit shocked that the sound from the laptop sounded more coherent with more dimensionality so I then knew the issue wasn't with the amp.
A bit stumped with nothing to lose I put the old tubes back in and decided to give it some run time. I've had it playing constant on repeat for about 60 hrs now and am finding that every time I go back to it the sound has improved slightly.
The soundstaging has improved and am getting better soundstage depth detail coming through but the whole thing sounding more coherent, focused and musical now.
Could it be it needed more running in?
I will see if it continues to improve. This is my first foray into the high end territory, but what I want to know is what should I expect from the CD8 and how musically convincing should it sound?

I still cannot get used to the vile green display though. Does anyone know if ARC only uses one shade of green in its gear or if this can be changed?