I know enclosure design + T/S parameters will indicate low frequency rolloff. I've modeled that in WinISD eval version, so I suppose that covers that end? But what about high frequency extension? In one or two other threads here, I've seen mention of an electrical T/S parameter that indicates high frequency extension. What exactly is that, and how is it used to determine high frquency extension? Is that influenced heavily by enclosure design, or is it essentially dependant only on the driver? Are there other factors to consider other than frequency response to choose an appropriate driver for a certain frequency range (e.g., a mid-bass passband from ~80Hz to ~200Hz)? i.e., I know driver size and frequency have some relationship (as in above a certain size for a given frequency, the driver no longer looks like a point source)... how critical is that?