when I switched from the 458 monos to the 468 monos it was hard to say exactly when they stopped improving incrementally. the initial bump up from the 458's was decided, but subtle in some ways. not sure I agree with 900 hours, but maybe. more like 300-400 hours as I recall.Mike, I noticed that Jacob mentioned in his review that his 468 amps took nearly 900 hours (going by memory here) to fully break-in!!! Is that your experience as well and are the 108 amps the same? This will certainly make auditioning a challenge as not many stockists around and then the amps must be fully run-in as well.
OTOH I do recall my initial experience in 2004 with the dart stereo 108 version A' which had a very extended break in time, maybe a month. and at first I was not sure they were for me. my friend Jonathan encouraged me to have patience, so I did......and was eventually rewarded.
what darTZeel does is about the whole first watt and refinement aspect of the music. it has to breathe freely.