moverbob,
in the studio line of paradigm's, they are on v.5. to my understanding, studio v.4's use the same tweeter, different midbass. the studio line is still made in canada, as are the signature line. the monitor line is now made in china. the difference between the monitor series and the studio series is fairly substantial in my oppinion. i feel that the studio line is far more musical. you need to look at the sensitiviy rating of a speaker to determine how well a lower powered amp like yours will play them. the studio 20's need some power to sound good, so your onkyo may not do the trick. i didn't think about zu audio, but now that i have, you might want to look into them. a while back they were offering zu omen standard's for 1,000. these are awesome speakers, built by cool people who care. the zu speakers are also incredibly efficient, meaning that your onkyo will push them without a problem. my vote would be to start checking out some zu's :-)