When you say it recommends speakers between 6 and 16ohms, does it specifically say not to use speakers below 6 ohm? I'd heard the QX2 through a Marantz NR1509 which does not have a 4ohm load specified but it drove it just fine. Newer AVRs and amps usuallydon't have a problem driving 4ohm loads but it's a good idea to call up the manufacturer - Onkyo directly and confirm.
This is going to come as a rude shock but your Onkyo AVR probably can't put out 130w per channel. Or can put out only 130w through one channel which gets drastically reduced when two or more channels are playing. Or worse still, 130w is rated at a very high THD, usually greater than 0.1% which is considered too high and unlistenable. On the other hand, the speakers are rated at the maximum power they can handle. Now assuming the direct case even scenario which is that your AVR can actually put out 130w per channel at <0.1%THD (no chance), the question you need to ask yourself is whether you ever listen to the music with the volume maxed out. If you don't, you're probably not using all the power on tap. Take for example the Porsche Cayenne - a favourite amongst soccer moms. It's a blazing fast SUV with some versions of it having in excess of 500bhp. It can do 0-60mph in less than 4 seconds and rated top speed is above 170mph. Simply because the soccer moms in question may not have been able to use the entire 500bhp on tap to accelerate at that rate and hit that top speed because they didn't possess the requisite skills (i suppose most of us can't btw), does it mean that the soccer moms couldn't drive the car at all? In your case, if the speakers are rated at a low power rating, simply don't crank up your AVR volume. I've used my altec Lansing mx5021 whose satellites are rated at 20w per channel with my Marantz sr6013 which is rated at 105w for a 2 channel load at <0.1% load and upon listening at reasonable volumes, the speakers survived just fine.
Depends on subjective taste. But more importantly, good sound does not get old. Newer speakers simply try to achieve better sound quality at a lower price point, especially so after andrew Jones did a number with his pioneer line and the new elacs. Nowadays, most manufacturers are trying to replicate that mojo.
Also, speakers are hardy so age is usually not a factor if maintained well. have a look at the condition before putting your money down. The Dynaudios are highly regarded speakers with many happy owners whereas the mission QX2s are the perfect all-rounders in my books. You can't go wrong with either.
All the best mate.
Cheers
