Honestly, that doesn't seem like that good of a deal. not bad but not that good either. My math is as follows, you sell the 650s at 250-275 + the 330 that you'd need to pay. So your "cost" would in fact be anywhere from 580-605. Don't the RS-1s go for around 525-500? The only exception that I would see is if they area pair with low hours ie: less than 50 or so or are one of the earlier ones with the wood box, assuming you care about that.