Hey shanmag, you are correct the Perfects are 4 ohm speakers. Any of the amps would be fine, but more power is usually never a bad thing. Actually, one of the Infinity reps told me that they prefer to run at least 150 watts RMS to really make the Perfects shine and handle the increased impedance at the crossover point. However, I have a friend who runs an Alpine amp rated at 75 X 2 RMS into 4 ohms and his Perfects sound great. I don't think you could go wrong with either of those amps power-wise, however, the JL is definitely a better quality amp and might offer noticeably better sound quality. I actually have a set of the Perfect 6.1's that I intend to sell in about a week or so if you are interested. I have had them for a couple months and they have been pampered. They are as close to new as a used set can get and I would let them go for $150 plus actual shipping costs to the buyers location. I have accounts with ebay and Paypal as well to assure a legitimate and efficient transaction. If you are interested let me know, and if not then good luck with your system. The Perfects are very nice and will not disappoint if you decide on them. Thanks.
Stay away from the PPI DCX series amps. PC/PCX and Art Series are good amps, but the DCX is less than notable on reliability.
THe only reason to run more than one set of speakers is so that passengers in the back can have rear fill. Other than that it is useless. It distracts from the music in front of you, and it cost more money to buy anopther set and then power them. There really is no point in having rear speakers.