Hi Michael_A,
Seems to me you did a pretty good job on your own of center-channel "alignment." I don't know of any particular discs that address this, but your technique of playing the stereo disc, noting where the center image is, and then aligning the center speaker with it seems to be excellent.
By the way, your discovery of how different your VP150 sounded in a different locations just backs up what I'm always trying to hammer home--that simply moving a speaker a few feet in a given room may introduce quite dramatic differences in the speaker's sound.
Indeed, in multiple tests of speakers which I participated in using scientific double-blind techniques, the same speaker would often be ranked very differently just by moving it to a different position (or if the listener moved to a different chair in the room). To average out these effects, we would judge each speaker in each one of four locations in the room, and from each of five different seating postiions. This would take days of listening, of course, but it proved to be extremely reliable and repeatable with any set of listeners with normal hearing. In other words, good speakers would receiver virtually identical high rankings from different listeners and bad speakers would get similarly low rankings, the upshot being that people with normal hearing tend to agree very consistently on what constitutes "good sound" and "bad sound".
Regards,
