Amp damping factor?


OK need some technical info. I was told by a reputable source that I should buy an amp that had a high damping factor >100 and preferably closer to 150-200. In looking at this in the specs for many units it seems this might be over-rated. I have been looking at some vintage Mac gear and their numbers are like 10-40? Is that an age thing and modern equipment is just that much better? Or is there a tradeoff I dont know about?
joekapahulu
1st, DF is just a spec, If all manu. measure the same, you should be able to compare. Not that this would make it mean any more or less!

Also, propagation delay is as good a reason as any why certain bi-amp combinations don't work out. 1milisecond is roughly 14" at the speed of sound and will result in phase/time smear effects. Even I can hear that! Pair a fast amp with a slow amp and you could quite possibly get to that level.
Sorry for the late post, but I have a question about DF. I own an ARC tube amp. I just happened to notice that most of the tube amps in the ARC line have pretty low DFs, e.g, less than 20. Nevertheless, most of the ARC tube amps sound great. So what's all the hubbabaloo about DF?? Does it matter that most if not all ARC tube amps use output trannys?
Magfan, I read the posts. I am not an electronics techie, so most of the discussion went over my head. Perhaps Kijanki will pick my post up and answer in layman's terms my question:

"I just happened to notice that most of the tube amps in the ARC line have pretty low DFs, e.g, less than 20. Nevertheless, most of the ARC tube amps sound great. So what's all the hubbabaloo about DF?? Does it matter that most if not all ARC tube amps use output trannys?"

Thanks
Bifwynne, It is a trade-off. Amplifiers with very high DF use a lot of negative feedback that enhances bright sounding odd harmonics.

How much of DF do you need? It depends on the speaker damping and room acoustics and perhaps many other factors. I would not even consider DF in my amp selection.